Thursday, December 25, 2008

Whitewater rafts

Whitewater rafts

Rafts were originally the simplest form of man’s transportation in water and were then made of several logs, planks or reeds which were fastened together. Nowadays, inflatable boat were used as rafts which were later adopted by the military for beach assaults. It consists of very durable, multi-layered rubberized or vinyl fabrics with several independent air chambers. Its length varies between 3.5 m (11 ft) and 6 m (20 ft), the width between 1.8 m (6 ft) and 2.5 m (8 ft). The exception to this size rule is usually the packraft, which is designed as a portable single-person raft and may be as small as 1.5m long and weigh as little as 4 lbs.
Rafts come in a few different forms. In Europe the most common is the symmetrical raft steered with a paddle at the stern. Other types are the asymmetrical, rudder-controlled raft and the symmetrical raft with central helm (oars). Rafts are usually propelled with ordinary paddles and typically hold 4 to 12 persons. In Russia rafts are often hand made and are often a catamaran style with two inflatable tubes attached to a frame. Pairs of paddlers navigate these rafts. Catamaran style rafts have become popular in the western United States as well, but are typically rowed instead of paddled.
Rivers with high current are used for White water rafting. Specially, White Water Rafting is popular in Nepal due to high current of water falling through hills and rocky mountains.

Classes of Whitewater

Class 1: Very small rough areas, requires no maneuvering. (Skill Level: None)

Class 2: Some rough water, maybe some rocks, might require maneuvering.(Skill Level: Basic Paddling Skill)

Class 3: Whitewater, small waves, maybe a small drop, but no considerable danger. May require significant maneuvering.(Skill Level: Experienced paddling skills)

Class 4: Whitewater, medium waves, maybe rocks, maybe a considerable drop, sharp maneuvers may be needed. (Skill Level: Whitewater Experience)

Class 5: Whitewater, large waves, possibility of large rocks and hazards, possibility of a large drop, requires precise maneuvering (Skill Level: Advanced Whitewater Experience)

Class 6: Class 6 rapids are considered to be so dangerous as to be effectively unnavigable on a reliably safe basis. Rafters can expect to encounter substantial whitewater, huge waves, huge rocks and hazards, and/or substantial drops that will impart severe impacts beyond the structural capacities and impact ratings of most all rafting equipment. Traversing a Class 6 rapid has a dramatically increased likelihood of ending in serious injury or death compared to lesser classes. (Skill Level: Successful completion of a Class 6 rapid without serious injury or death is widely considered to be a matter of luck or extreme skill)

Thursday, December 18, 2008



Rafting or whitewater rafting is a challenging recreational activity utilizing a raft to navigate a river or other bodies of water. This is usually done on whitewater or different degrees of rough water, in order to thrill and excite the raft passengers. The development of this activity as a leisure sport has become popular since the mid 1970s.


Rafting is one of the earliest means of transportation, used as a means for shipping people, hunting, and transferring food.
In 1842, Lieutenant John Fremont of the U.S. Army first journalized his rafting expedition on the Platte River. Horace H. Day designed the equipment he used in rafting. Day’s rafts were constructed from four independent rubber cloth tubes and wrap-around floor.
In 1960s, rafting was then recognized and paths like Grand Canyon were routed and whitewater rafting companies were established.
In 1970s, rafting marked its major development as a leisure sport when it was then included in the Munich Olympic Games.
In 1980s, as rafting continued to gain its popularity, many rivers were opened for rafting activities including rivers in South America and Africa.
In 1990s, rafting was included in major game events like the Barcelona Games in 1992, Atlanta Games in 1996, and the whitewater events of the Summer Olympic Games hosted by Ocoee River in Tennessee Valley. In addition, the International Federation of Rafting was instituted in 1997 and in 1999 the first Official International Championship was held.
Currently, river rafting is still gaining popularity among extreme water sports in order to thrill and excite the raft passengers.

Friday, December 12, 2008

Coal fires

Coal fires

There are hundreds of coal fires burning around the world. Those burning underground can be difficult to locate and many cannot be extinguished. Fires can cause the ground above to subside, their combustion gases are dangerous to life, and breaking out to the surface can initiate surface wildfires. Coal seams can be set on fire by spontaneous combustion or contact with a mine fire or surface fire. A grass fire in a coal area can set dozens of coal seams on fire. Coal fires in China burn 109 million tons of coal a year, emitting 360 million metric tons of CO2. This contradicts the ratio of 1:1.83 given earlier, but it amounts to 2-3% of the annual worldwide production of CO2 from fossil fuels, or as much as emitted from all of the cars and light trucks in the United States. In Centralia, Pennsylvania (a borough located in the Coal Region of the United States) an exposed vein of coal ignited in 1962 due to a trash fire in the borough landfill, located in an abandoned anthracite strip mine pit. Attempts to extinguish the fire were unsuccessful, and it continues to burn underground to this day. The Australian Burning Mountain was originally believed to be a volcano, but the smoke and ash comes from a coal fire which may have been burning for over 5,500 years.

At Kuh i Malik in Yagnob Valley, Tajikistan, coal deposits have been burning for thousands of years, creating vast underground labyrinths full of unique minerals, some of them very beautiful. Local people once used this method to mine ammoniac. This place has been well-known since the time of Herodotus, but European geographers mis-interpreted the Ancient Greek descriptions as the evidence of active volcanism in Turkestan (up to the 19th century, when Russian army invaded the area).

The reddish siltstone rock that caps many ridges and buttes in the Powder River Basin (Wyoming), and in western North Dakota is called porcelanite, which also may resemble the coal burning waste "clinker" or volcanic "scoria". Clinker is rock that has been fused by the natural burning of coal. In the Powder River Basin approximately 27 to 54 billion tons of coal burned within the past three million years. Wild coal fires in the area were reported by the Lewis and Clark Expedition as well as explorers and settlers in the area.
Production trends Coal output in 2005. A coal mine in Jharkhand, India. India has about 10% of world's coal reserves.In 2006, China was the top producer of coal with 38% share followed by the USA and India, reports the British Geological Survey.

Friday, December 5, 2008

Energy density

Energy density

The energy density of coal, i.e. its heating value, is roughly 24 megajoules per kilogram.
The energy density of coal can also be expressed in kilowatt-hours for some unit of mass, the units that electricity is most commonly sold in, to estimate how much coal is required to power electrical appliances. One kilowatt-hour is 3.6 MJ, so the energy density of coal is 6.67 kW·h/kg. The typical thermodynamic efficiency of coal power plants is about 30%, so of the 6.67 kW·h of energy per kilogram of coal, 30% of that—2.0 kW·h—can successfully be turned into electricity; the rest is waste heat. So coal power plants obtain approximately 2.0 kW·h per kilogram of burned coal.
As an example, running one 100 watt computer for one year requires 876 kW·h (100 W × 24 h/day × 365 {days in a year} = 876000 W·h = 876 kW·h). Converting this power usage into physical coal consumption:
876kW.h/2.0kW.h/kg=438 Kg of Coal=966 pounds of Coal
It takes 438 kg (966 lb) of coal to power a computer for one full year. One should also take into account transmission and distribution losses caused by resistance and heating in the power lines, which is in the order of 5–10%, depending on distance from the power station and other factors.
Relative carbon costBecause coal is at least 50% carbon (by mass), then 1 kg of coal contains at least 0.5 kg of carbon, which is
where 1 mol is equal to NA (Avogadro Number) particles. This combines with oxygen in the atmosphere during combustion, producing carbon dioxide, with an atomic weight of (12 + 16 × 2 = mass(CO2) = 44 kg/kmol), so 1⁄24 kmol of CO2 is produced from the 1⁄24 kmol present in every kilogram of coal, which once trapped in CO2 weighs approximately
. This can be used to put a carbon-cost of energy on the use of coal power. Since the useful energy output of coal is about 30% of the 6.67 kW·h/kg(coal), we can say about 2 kW·h/kg(coal) of energy is produced. Since 1 kg coal roughly translates as 1.83 kg of CO2, we can say that using electricity from coal produces CO2 at a rate of about 0.915 kg/(kW·h), or about 0.254 kg/MJ.
This estimate compares favourably with the U.S. Energy Information Agency's 1999 report on CO2 emissions for energy generation, which quotes a specific emission rate of 950 g CO2/(kW·h). By comparison, generation from oil in the U.S. was 890 g CO2/(kW·h), while natural gas was 600 g CO2/(kW·h). Estimates for specific emission from nuclear power, hydro, and wind energy vary, but are about 100 times lower. See environmental effects of nuclear power for estimates.

Friday, November 28, 2008

Coal as a traded commodity

Coal as a traded commodity

The price of coal has gone up from around $30 per short ton in 2000 to around $123.50 per short ton as of June 25th, 2008.
In North America, a Central Appalachian coal futures contract is currently traded on the New York Mercantile Exchange (trading symbol QL). The trading unit is 1,550 short tons per contract, and is quoted in U.S. dollars and cents per ton. Since coal is the principal fuel for generating electricity in the United States, the futures contract provides coal producers and the electric power industry an important tool for hedging and risk management.
In addition to the NYMEX contract, the IntercontinentalExchange (ICE) has European (Rotterdam) and South African (Richards Bay) coal futures available for trading. The trading unit for these contracts is 5,000 metric tons, and are also quoted in U.S. dollars and cents per ton.
Cultural usageCoal is the official state mineral of Kentucky and the official state rock of Utah. Both U.S. states have a historic link to coal mining.
Some cultures uphold that children who misbehave will receive coal from Santa Claus for Christmas in their stockings instead of presents.
It is also customary and lucky in Scotland to give coal as a gift on New Year's Day. It happens as part of First-Footing and represents warmth for the year to come.

Environmental effects

There are a number of adverse environmental effects of coal mining and burning, specially in power stations.
These effects include:
  • release of carbon dioxide and methane, both of which are greenhouse gases, which are causing climate change and global warming according to the IPCC. Coal is the largest contributor to the human-made increase of CO2 in the air.
  • waste products including uranium, thorium, and other heavy metals
  • acid rain
  • interference with groundwater and water table levels impact of water use on flows of rivers and consequential
  • impact on other land-uses
  • dust nuisance
  • subsidence above tunnels, sometimes damaging infrastructure
  • rendering land unfit for other uses.
  • coal-fired power plants without effective fly ash capture are one of the largest sources of human-caused background radiation exposure.

Saturday, November 22, 2008

Liquefaction - Coal-To-Liquids (CTL)

Coals can also be converted into liquid fuels like gasoline or diesel by several different processes. The Fischer-Tropsch process of indirect synthesis of liquid hydrocarbons was used in Nazi Germany for many years and is today used by Sasol in South Africa. Coal would be gasified to make syngas (a balanced purified mixture of CO and H2 gas) and the syngas condensed using Fischer-Tropsch catalysts to make light hydrocarbons which are further processed into gasoline and diesel. Syngas can also be converted to methanol, which can be used as a fuel, fuel additive, or further processed into gasoline via the Mobil M-gas process.A direct liquefaction process Bergius process (liquefaction by hydrogenation) is also available but has not been used outside Germany, where such processes were operated both during World War I and World War II. SASOL in South Africa has experimented with direct hydrogenation. Several other direct liquefaction processes have been developed, among these being the SRC-I and SRC-II (Solvent Refined Coal) processes developed by Gulf Oil and implemented as pilot plants in the United States in the 1960s and 1970s.
Another direct hydrogenation process was explored by the NUS Corporation in 1976 and patented by Wilburn C. Schroeder. The process involved dried, pulverized coal mixed with roughly 1wt% molybdenum catalysts. Hydrogenation occurred by use of high temperature and pressure synthesis gas produced in a separate gasifier. The process ultimately yielded a synthetic crude product, Naphtha, a limited amount of C3/C4 gas, light-medium weight liquids (C5-C10) suitable for use as fuels, small amounts of NH3 and significant amounts of CO2.
Yet another process to manufacture liquid hydrocarbons from coal is low temperature carbonization (LTC). Coal is coked at temperatures between 450 and 700°C compared to 800 to 1000°C for metallurgical coke. These temperatures optimize the production of coal tars richer in lighter hydrocarbons than normal coal tar. The coal tar is then further processed into fuels. The Karrick process was developed by Lewis C. Karrick, an oil shale technologist at the U.S. Bureau of Mines in the 1920s.
All of these liquid fuel production methods release carbon dioxide (CO2) in the conversion process, far more than is released in the extraction and refinement of liquid fuel production from petroleum. If these methods were adopted to replace declining petroleum supplies, carbon dioxide emissions would be greatly increased on a global scale. For future liquefaction projects, Carbon dioxide sequestration is proposed to avoid releasing it into the atmosphere, though no pilot projects have confirmed the feasibility of this approach on a wide scale. As CO2 is one of the process streams, sequestration is easier than from flue gases produced in combustion of coal with air, where CO2 is diluted by nitrogen and other gases. Sequestration will, however, add to the cost.
The reaction of coal and water using high temperature heat from a nuclear reactor offers promise of liquid transport fuels that could prove carbon-neutral compared to petroleum use. The development of a reliable nuclear reactor that could provide 900 to 1000 deg C process heat, such as the pebble bed reactor, would be necessary.
Coal liquefaction is one of the backstop technologies that could potentially limit escalation of oil prices and mitigate the effects of transportation energy shortage that some authors have suggested could occur under peak oil. This is contingent on liquefaction production capacity becoming large enough to satiate the very large and growing demand for petroleum. Estimates of the cost of producing liquid fuels from coal suggest that domestic U.S. production of fuel from coal becomes cost-competitive with oil priced at around 35 USD per barrel, (break-even cost). The current price of oil, as of July 11, 2008, is 145 USD per barrel. This makes coal a viable financial alternative to oil for the time being, although current production is small.
Among commercially mature technologies, advantage for indirect coal liquefaction over direct coal liquefaction are reported by Williams and Larson (2003). Estimates are reported for sites in China where break-even cost for coal liquefaction may be in the range between 25 to 35 USD/barrel of oil.
Intensive research and project developments have been implemented from 2001. The World CTL Award is granted to personalities having brought eminent contribution to the understanding and development of Coal liquefaction. The 2009 presentation ceremony will take place in Washington DC (USA) at the World CTL 2009 Conference (25-27 March, 2009).

Saturday, November 15, 2008

Coking and use of coke

Coking and use of coke

Coke is a solid carbonaceous residue derived from low-ash, low-sulfur bituminous coal from which the volatile constituents are driven off by baking in an oven without oxygen at temperatures as high as 1,000 °C (1,832 °F) so that the fixed carbon and residual ash are fused together. Metallurgic coke is used as a fuel and as a reducing agent in smelting iron ore in a blast furnace. Coke from coal is grey, hard, and porous and has a heating value of 24.8 million Btu/ton (29.6 MJ/kg). Some cokemaking processes produce valuable by-products that include coal tar, ammonia, light oils, and "coal gas".
Petroleum coke is the solid residue obtained in oil refining, which resembles coke but contains too many impurities to be useful in metallurgical applications.


High prices of oil and natural gas are leading to increased interest in "BTU Conversion" technologies such as gasification, methanation and liquefaction.
Coal gasification breaks down the coal into smaller molecular weight molecules, usually by subjecting it to high temperature and pressure, using steam and measured amounts of oxygen. This leads to the production of syngas, a mixture mainly consisting of carbon monoxide (CO) and hydrogen (H2).
In the past, coal was converted to make coal gas, which was piped to customers to burn for illumination, heating, and cooking. At present, the safer natural gas is used instead. South Africa still uses gasification of coal for much of its petrochemical needs.
The Synthetic Fuels Corporation was a U.S. government-funded corporation established in 1980 to create a market for alternatives to imported fossil fuels (such as coal gasification). The corporation was discontinued in 1985.
Gasification is also a possibility for future energy use, as the produced syngas can be cleaned-up relatively easily leading to cleaner burning than burning coal directly (the conventional way). The cleanliness of the cleaned-up syngas is comparable to natural gas enabling to burn it in a more efficient gas turbine rather than in a boiler used to drive a steam turbine. Syngas produced by gasification can be CO-shifted meaning that the combustible CO in the syngas is transferred into carbon dioxide (CO2) using water as a reactant. The CO-shift reaction also produces an amount of combustible hydrogen (H2) equal to the amount of CO converted into CO2. The CO2 concentrations (or rather CO2 partial pressures) obtained by using coal gasification followed by a CO-shift reaction are much higher than in case of direct combustion of coal in air (which is mostly nitrogen). These higher concentrations of carbon dioxide make carbon capture and storage much more economical than it otherwise would be.

Sunday, November 9, 2008

Uses today

Coal as a Fuel
Coal is primarily used as a solid fuel to produce electricity and heat through combustion. World coal consumption is about 6.2 billion tons annually, of which about 75% is used for the production of electricity. China produced 2.38 billion tons in 2006 and India produced about 447.3 million tons in 2006. 68.7% of China's electricity comes from coal. The USA consumes about 1.053 billion tons of coal each year, using 90% of it for generation of electricity. The world in total produced 6.19 billion tons of coal in 2006.
When coal is used for electricity generation, it is usually pulverized and then burned in a furnace with a boiler. The furnace heat converts boiler water to steam, which is then used to spin turbines which turn generators and create electricity. The thermodynamic efficiency of this process has been improved over time. "Standard" steam turbines have topped out with some of the most advanced reaching about 35% thermodynamic efficiency for the entire process, which means 65% of the coal energy is waste heat released into the surrounding environment. Old coal power plants, especially "grandfathered" plants, are significantly less efficient and produce higher levels of waste heat.
The emergence of the supercritical turbine concept envisions running a boiler at extremely high temperatures and pressures with projected efficiencies of 46%, with further theorized increases in temperature and pressure perhaps resulting in even higher efficiencies.
Other efficient ways to use coal are combined cycle power plants, combined heat and power cogeneration, and an MHD topping cycle.
Approximately 40% of the world electricity production uses coal. The total known deposits recoverable by current technologies, including highly polluting, low energy content types of coal (i.e., lignite, bituminous), might be sufficient for 300 years' use at current consumption levels, although maximal production could be reached within decades.
A more energy-efficient way of using coal for electricity production would be via solid-oxide fuel cells or molten-carbonate fuel cells (or any oxygen ion transport based fuel cells that do not discriminate between fuels, as long as they consume oxygen), which would be able to get 60%–85% combined efficiency (direct electricity + waste heat steam turbine).Currently these fuel cell technologies can only process gaseous fuels, and they are also sensitive to sulfur poisoning, issues which would first have to be worked out before large scale commercial success is possible with coal. As far as gaseous fuels go, one idea is pulverized coal in a gas carrier, such as nitrogen. Another option is coal gasification with water, which may lower fuel cell voltage by introducing oxygen to the fuel side of the electrolyte, but may also greatly simplify carbon sequestration. However, this technology has been criticised as being inefficient, slow, risky and costly, while doing nothing about total emissions from mining, processing and combustion.

Sunday, November 2, 2008

Early use of Coal

Early use

China Coal Information Institute reports the Chinese mined coalstone for fuel 10,000 years ago at the time of the New Stone Age, or Neolithic Era. "People in Shanxi, now the largest coal production base, have been burning coal as fuel since then." Outcrop coal was used in Britain during the Bronze Age (2000-3000 years BC), where it has been detected as forming part of the composition of funeral pyres. It was also commonly used in the early period of the Roman occupation: Evidence of trade in coal (dated to about AD 200) has been found at the inland port of Heronbridge, near Chester, and in the Fenlands of East Anglia, where coal from the Midlands was transported via the Car Dyke for use in drying grain. Coal cinders have been found in the hearths of villas and military forts, particularly in Northumberland, dated to around AD 400. In the west of England contemporary writers described the wonder of a permanent brazier of coal on the altar of Minerva at Aquae Sulis (modern day Bath) although in fact easily-accessible surface coal from what became the Somerset coalfield was in common use in quite lowly dwellings locally.
There is no evidence that the product was of great importance in Britain before the High Middle Ages, after about AD 1000. Mineral coal came to be referred to as "seacoal," probably because it came to many places in eastern England, including London, by sea. This is accepted as the more likely explanation for the name than that it was found on beaches, having fallen from the exposed coal seams above or washed out of underwater coal seam outcrops. These easily accessible sources had largely become exhausted (or could not meet the growing demand) by the 13th century, when underground mining from shafts or adits was developed. In London there is still a Seacoal Lane and a Newcastle Lane (from the coal-shipping city of Newcastle) where in the seventeenth century coal was unloaded at wharves along the River Fleet. An alternative name was "pitcoal," because it came from mines. It was, however, the development of the Industrial Revolution that led to the large-scale use of coal, as the steam engine took over from the water wheel.

Monday, October 27, 2008



Coal is a fossil fuel formed in ecosystems where plant remains were preserved by water and mud from oxidization and biodegradation, thus sequestering atmospheric carbon. Coal is a readily combustible black or brownish-black rock. It is a sedimentary rock, but the harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. It is composed primarily of carbon and hydrogen along with small quantities of other elements, notably sulfur. Coal is extracted from the ground by coal mining, either underground mining or open pit mining (surface mining).
Coal is the largest source of fuel for the generation of electricity world-wide, as well as the largest world-wide source of carbon dioxide emissions. Carbon dioxide is a greenhouse gas and these emissions contribute to climate change and global warming.] In terms of carbon dioxide emissions, coal is slightly ahead of petroleum and about double that of natural gas.Types of coalAs geological processes apply pressure to dead biotic matter over time, under suitable conditions it is transformed successively into
  • Peat, considered to be a precursor of coal. It has industrial importance as a fuel in some countries, for example, Ireland and Finland.
    Lignite, also referred to as brown coal, is the lowest rank of coal and used almost exclusively as fuel for electric power generation. Jet is a compact form of lignite that is sometimes polished and has been used as an ornamental stone since the Iron Age.
  • Sub-bituminous coal, whose properties range from those of lignite to those of bituminous coal and are used primarily as fuel for steam-electric power generation. Additionally, it is an important source of light aromatic hydrocarbons for the chemical synthesis industry.
  • Bituminous coal, a dense mineral, black but sometimes dark brown, often with well-defined bands of bright and dull material, used primarily as fuel in steam-electric power generation, with substantial quantities also used for heat and power applications in manufacturing and to make coke.
  • Anthracite, the highest rank; a harder, glossy, black coal used primarily for residential and commercial space heating. It may be divided further into metamorphically altered bituminous coal and petrified oil, as from the deposits in Pennsylvania.
  • Graphite, technically the highest rank, but difficult to ignite and is not so commonly used as fuel: it is mostly used in pencils and, when powdered, as a lubricant.

Tuesday, October 21, 2008

Coal Mine-2 part

Large mammals and other animals displaced from their home ranges may be forced to use adjacent areas already stocked to carrying capacity. This overcrowding usually results in degradation of remaining habitat, lowered carrying capacity, reduced reproductive success, increased interspecies and intraspecies competition, and potentially greater losses to wildlife populations than the number of originally displaced animals.Removal of soil and rock overburden covering the coal resource, if improperly done, causes burial and loss of top soil, exposes parent material, and creates vast infertile wastelands. Pit and spoil areas are not capable of providing food and cover for most species of wildlife. Without rehabilitation, these areas must go through a weathering period, which may take a few years or many decades, before vegetation is established and they become suitable habitat. With rehabilitation, impacts on some species are less severe. Humans cannot immediately restore natural biotic communities.

We can, however, assist nature through reclamation of land and rehabilitation efforts geared to wildlife needs. Rehabilitation not geared to the needs of wildlife species, or improper management of other land uses after reclamation, can preclude reestablishment of many members of the original fauna.Degradation of aquatic habitats has often been a major impact from surface mining and may be apparent to some degree many miles from a mining site. Sediment contamination of surface water is common with surface mining. Sediment yields may increase 1000 times over their former level as a direct result of strip mining. In some circumstances, especially those involving disturbance of unconsolidated soils, approximately one acre foot of sediment may be produced annually for every 80 acres of disturbed land.The effects of sediment on aquatic wildlife vary with the species and amount of contamination. High sediment loads can kill fish directly, bury spawning beds, reduce light transmission, alter temperature gradients, fill in pools, spread stream flows over wider, shallower areas, and reduce production of aquatic organisms used as food by other species. These changes destroy the habitat of some valued species and may enhance habitat for less desirable species. Existing conditions are already marginal for some freshwater fish in the United States. Sedimentation of these waters can result in their elimination. The heaviest sediment pollution of a drainage normally comes within five to 25 years after mining. In some areas, unrevegetated spoil piles continue to erode even 50 to 65 years after mining.The presence of acid forming materials exposed as a result of surface mining can affect wildlife by eliminating habitat and by causing direct destruction of some species. Lesser concentrations can suppress productivity, growth rate, and reproduction of many aquatic species. Acids, dilute concentrations of heavy metals, and high alkalinity can cause severe wildlife damage in some areas. The duration of acidic waste pollution can be long term. Estimates of the time required to leach exposed acidic materials in the Eastern United States range from 800 to 3000 years.In some situations, surface mining may have beneficial impacts on some wildlife. Where large, continuous tracts of forest, bush land, sagebrush, or grasslands are broken up during mining, increased edges and openings are created.

Preferred food and cover plants can be established in these openings to benefit a wide variety of wildlife. Under certain conditions, creation of small lakes in the mined area may also be beneficial. These lakes and ponds may become important water sources for a variety of wildlife inhabiting adjacent areas. Many lakes formed in mine pits are initially of poor quality as aquatic habitat after mining, due to lack of structure, aquatic vegetation, and food species. They may require habitat enhancement and management to be of significant wildlife value.Surface mining operations and coal transportation facilities are fully dedicated to coal production for the life of a mine. Mining activities incorporating little or no planning to establish postmining land use objectives usually result in reclamation of disturbed lands to a land use condition not equal to the original use. Existing land uses such as livestock grazing, crop and timber production are temporarily eliminated from the mining area. High value, intensive land use areas like urban and transportation systems are not usually affected by mining operations.

If mineral values are sufficient, these improvements may be removed to an adjacent area.Surface mining operations have produced cliff-like highwalls as high as 200 feet in the United States. Such highwalls may be created at the end of a surface mining operation where stripping becomes uneconomic, or where a mine reaches the boundary of a current lease or mineral ownership. These highwalls are hazards to people, wildlife, and domestic livestock. They may impede normal wildlife migration routes. Steep slopes also merit special attention because of the significance of impacts associated with them when mined. While impacts from contour mining on steep slopes are of the same type as all mining, the severity of these impacts increase as the degree of slope increases. This is due to increased difficulties in dealing with problems of erosion and land stability on steeper slopes.Fires sometimes occur in coal beds underground. When coal beds are exposed, the fire risk is increased. Weathered coal can also increase ground temperatures if it is left on the surface. Almost all fires in solid coal are ignited by surface fires caused by people or lightning. Spontaneous combustion is caused when coal oxidizes and air flow is insufficient to dissipate heat, but this occurs only in stockpiles and waste piles, not in bedded coals underground. Where coal fires occur, there is attendant air pollution from emission of smoke and noxious fumes into the atmosphere. Coal seam fires may burn underground for decades, threatening destruction of forests, homes, schools, churches, roadways and other valuable infrastructure. Spontaneous combustion is common in coal stockpiles and refuse piles at mine sites.Adverse impacts on geological features of human interest may occur in a surface mine area. Geomorphic and geophysical features and outstanding scenic resources may be sacrificed by indiscriminate mining. Paleontological, cultural, and other historic values may be endangered due to disruptive activities of blasting, ripping, and excavating coal. Stripping of overburden eliminates and destroys all archeological and historic features unless they are removed beforehand. Extraction of coal by surface mining disrupts virtually all esthetic elements of the landscape, in some cases only temporarily. Alteration of land forms often imposes unfamiliar and discontinuous configurations. New linear patterns appear as material is extracted and waste piles are developed. Different colors and textures are exposed as vegetative cover is removed and overburden dumped to the side. Dust, vibration, and diesel exhaust odors are created, affecting sight, sound, and smell. Some members of local communities may find such impacts disturbing or unpleasant.Due to intensive mechanization, surface mines may require fewer workers than underground mines with equivalent production, although this does not appear to be true in Indonesia. The influence on human populations from surface mining is therefore not generally as significant as with underground mines. In low population areas, however, local populations cannot provide needed labor so there is migration to the area because new jobs are available at a mine. Unless adequate advance planning is done by local government and mine operators, new populations may cause overcrowded schools, hospitals and demands on public services that cannot easily be met. Some social instability may be created in nearby communities by surface coal mining.Many impacts can be minimized but may not be eliminated entirely by use of best mining practices either voluntarily or to comply with government regulatory programs. Financial incentives to minimize costs of production may minimize use of best mining practices in the absence of effective regulation. Some temporary destruction of the land surface is an environmental price we pay for utilization of coal resources. The scale of disturbance, its duration, and the quality of reclamation are largely determined by management of the operation during mining.

Wednesday, October 15, 2008

Environmental impacts

Environmental impacts

Coal mining can result in a number of adverse effects on the environment. Open cast coal mines leaves areas of land that are no longer usable and leaves a scarred landscape with no scenic value. Rehabilitation can mitigate some of these concerns. Mine tailing dumps produce acid mine drainage which can seep into waterways and aquifers with consequences on ecological and human health. Subsidence of land surfaces due to collapse of mine tunnels can also occur. During the mining operation methane, a potent greenhouse gas and a constituent of fire damp, can be released.
Wherever it occurs in the world, surface mining of coal completely eliminates existing vegetation, destroys the genetic soil profile, displaces or destroys wildlife and habitat, degrades air quality, alters current land uses, and to some extent permanently changes the general topography of the area mined. The community of micro organisms and nutrient cycling processes are upset by movement, storage, and redistribution of soil.
Generally, soil disturbance and associated compaction result in conditions conducive to erosion. Soil removal from the area to be surface mined alters or destroys many natural soil characteristics, and may reduce its productivity for agriculture or biodiversity. Soil structure may be disturbed by pulverization or aggregate breakdown.
Removal of vegetative cover and activities associated with construction of haul roads, stockpiling of topsoil, displacement of overburden and hauling of spoil and coal increase the quantity of dust around mining operations. Dust degrades air quality in the immediate area, can have adverse impacts on vegetative life, and may constitute a health and safety hazard for mine workers and nearby residents. The land surface, often hundreds of acres, is dedicated to mining activities until it can be reshaped and reclaimed. If mining is allowed, resident human populations must be resettled off the mine site, and economic activities such as agriculture or hunting and gathering food or medicinal plants are displaced, at least temporarily. What becomes of the land surface after mining is determined by the manner in which mining is conducted.
Surface mining can adversely impact the hydrology of any region. Deterioration of stream quality can result from acid mine drainage, toxic trace elements, high content of dissolved solids in mine drainage water, and increased sediment loads discharged to streams. Waste piles and coal storage piles can yield sediment to streams, and leached water from these piles can be acid and contain toxic trace elements. Surface waters may be rendered unfit for agriculture, human consumption, bathing, or other household uses. Controlling these impacts requires careful management of surface water flows into and out of mining operations.
Flood events can cause severe damage to improperly constructed or located coal haul roads, housing, coal crushing and washing plant facilities, waste and coal storage piles, settling basin dams, surface water diversion structures, and the mine itself. Besides the danger to life and property, large amounts of sediment and poor quality water may have detrimental effects many miles downstream from a mine site after a flood.
Ground water supplies may be adversely affected by surface mining. These impacts include drainage of usable water from shallow aquifers; lowering of water levels in adjacent areas and changes in flow directions within aquifers; contamination of usable aquifers below mining operations due to infiltration or percolation of poor quality mine water; and increased infiltration of precipitation on spoil piles. Where coal or carbonaceous shales are present, increased infiltration may result in increased runoff of poor quality water and erosion from spoil piles; recharge of poor quality water to shallow groundwater aquifers; or poor quality water baseflow to nearby streams. This may contaminate both ground water and nearby streams for long periods. Lakes formed in abandoned surface mining operations are more likely to be acid if there is coal or carbonaceous shale present in spoil piles, especially if these materials are near the surface and contain pyrites.
Surface mining of coal causes direct and indirect damage to wildlife. The impact on wildlife stems primarily from disturbing, removing, and redistributing the land surface. Some impacts are short-term and confined to the mine site; others may have far reaching, long term effects. The most direct effect on wildlife is destruction or displacement of species in areas of excavation and spoil piling. Mobile wildlife species like game animals, birds, and predators leave these areas. More sedentary animals like invertebrates, many reptiles, burrowing rodents and small mammals may be directly destroyed.
If streams, lakes, ponds or marshes are filled or drained, fish, aquatic invertebrates, and amphibians are destroyed. Food supplies for predators are reduced by destruction of these land and water species. Animal populations displaced or destroyed can eventually be replaced from populations in surrounding ranges, provided the habitat is eventually restored. An exception could be extinction of a resident endangered species.
Many wildlife species are highly dependent on vegetation growing in natural drainages. This vegetation provides essential food, nesting sites and cover for escape from predators. Any activity that destroys this vegetation near ponds, reservoirs, marshes, and wetlands reduces the quality and quantity of habitat essential for waterfowl, shore birds, and many terrestrial species. The commonly used head of hollow fill method for disposing of excess overburden is of particular significance to wildlife habitat in some locations. Narrow, steep sided, V shaped hollows near ridge tops are frequently inhabited by rare or endangered animal and plant species. Extensive placement of spoil in these narrow valleys eliminates important habitat for a wide variety of species, some of which may be rendered extinct.
Broad and long lasting impacts on wildlife are caused by habitat impairment. The habitat requirements of many animal species do not permit them to adjust to changes created by land disturbance. These changes reduce living space. The degree to which a species or an individual animal tolerates human competition for space varies. Some species tolerate very little disturbance. In instances where a particularly critical habitat is restricted, such as a lake, pond, or primary breeding area, a species could be eliminated.

Sunday, October 5, 2008

Coal Mine-Production

Coal is mined commercially in over 50 countries. Over 4 970 Mt of hard coal is currently produced, a nearly 80% increase over the past 25 years. In 2005, the world production of brown coal and lignite was 906 Mt, with Germany the world’s largest brown coal producer.
Coal production has grown fastest in Asia, while Europe has declined. The top five coal mining nations (figures in brackets are 2006 estimate of hard coal production) are:
  • China (2 482 Mt)
  • USA (990 Mt)
  • India (427 Mt)
  • Australia (309 Mt)
  • South Africa (244 Mt)
Most coal production is used in the country of origin, with around 16% of hard coal production being exported.
Global coal production is expected to reach 7 Gt in 2030, with China accounting for most of this increase. Steam coal production is projected to reach around 5200 Mt; coking coal 620 Mt; and brown coal 1200 Mt.
Coal reserves are available in almost every country worldwide, with recoverable reserves in around 70 countries. At current production levels, proven coal reserves are estimated to last 147 years.

Modern mining

Technological advancements have made coal mining today more productive than it has ever been. To keep up with technology and to extract coal as efficiently as possible modern mining personnel must be highly skilled and well trained in the use of complex, state-of-the-art instruments and equipment. Future coal miners have to be highly educated and many jobs require four-year college degrees. Computer knowledge has also become greatly valued within the industry as most of the machines and safety monitors are computerized.
In the United States, the increase in technology has significantly decreased the mining workforce from 335,000 coal miners working at 7,200 mines fifty years ago to 104,824 miners working in fewer than 2,000 mines today. As some might see this as a sign that coal is a declining industry its advances has reported an 83% increase of production from 1970 to 2004.

Dangers to miners

Historically, coal mining has been a very dangerous activity and the list of historical coal mining disasters is a long one. Open cut hazards are principally mine wall failures and vehicle collisions; underground mining hazards include roof collapse, attacks from the dreaded Balrog, and gas explosions. Most of these risks can be greatly reduced in modern mines, and multiple fatality incidents are now rare in some parts of the developed world.
However, in lesser developed countries and some developed countries, many miners continue to die annually, either through direct accidents in coal mines or through adverse health consequences from working under poor conditions. China, in particular, has the highest number of coal mining related deaths in the world, with official statistic 6,027 deaths in 2004. To compare, the USA reported 28 deaths in the same year. Coal production in China is twice that of the United States, while the number of coal miners is around 50 times that of the USA, making deaths in coal mines in China 4 times as common per worker (108 times as common per unit output) as in the USA.
When compared to industrial countries such as China, the U.S. fatality rate is low.[specify] However in 2006 fatal work injuries among U.S. miners doubled from the previous year, totaling 47.[16] These figures can in part be attributed to the Sago Mine disaster. The recent mine accident in Utah's Crandall Canyon Mine, where nine miners were killed and six entombed, speaks to the increase in occupational risks faced by U.S. miners.
Chronic lung diseases, such as pneumoconiosis (black lung) were once common in miners, leading to reduced life expectancy. In some mining countries black lung is still common, with 4000 new cases of black lung every year in the USA (4% of workers annually) and 10 000 new cases every year in China (0.2% of workers). Rates may be higher than reported in some regions.
Build-ups of a hazardous gas are known as damps, possibly from the German word "Dampf" which means steam or vapor:
  • Black damp: a mixture of carbon dioxide and nitrogen in a mine can cause suffocation.
  • After damp: similar to black damp, an after damp consists of carbon dioxide and nitrogen and forms after a mine explosion.
  • Fire damp: consists of mostly methane, a flammable gas.
  • Stink damp: so named for the rotten egg smell of the sulfur, a stink damp can explode.
  • White damp: air containing carbon monoxide which is toxic, even at low concentrations

Saturday, September 27, 2008

Underground mining

Underground mining

Coal wash plant in Clay County, Kentucky.Most coal seams are too deep underground for opencast mining and require underground mining, which method currently accounts for about 60% of world coal production. In deep mining, the room and pillar or bord and pillar method progresses along the seam, while pillars and timber are left standing to support the mine roof. Once room and pillar mines have been developed to a stopping point (limited by geology, ventilation, or economics), a supplementary version of room and pillar mining, termed second mining or retreat mining, is commonly started. This is when miners remove the coal in the pillars, thereby recovering as much coal from the coal seam as possible. A work area that is involved in pillar extraction is called a pillar section. Modern pillar sections use remote-controlled equipment, including large hydraulic mobile roof-supports, which can prevent cave-ins until the miners and their equipment have left a work area. The mobile roof supports are similar to a large dining-room table, but with hydraulic jacks for legs. After the large pillars of coal have been mined away, the mobile roof support's legs shorten and it is withdrawn to a safe area. The mine roof typically collapses once the mobile roof supports leave an area.

There are five principal underground mining methods:
  • Longwall mining accounts for about 50% of underground production. The longwall shearer has a face of 1,000 feet (300 m) or more. It is a sophisticated machine with a rotating drum that moves mechanically back and forth across a wide coal seam. The loosened coal falls on to a pan line that takes the coal to the conveyor belt for removal from the work area. Longwall systems have their own hydraulic roof supports which advance with the machine as mining progresses. As the longwall mining equipment moves forward, overlying rock that is no longer supported by coal is allowed to fall behind the operation in a controlled manner. The supports make possible high levels of production and safety. Sensors detect how much coal remains in the seam while robotic controls enhance efficiency. Longwall systems allow a 60-to-100% coal recovery rate when surrounding geology allows their use.
  • Continuous mining utilizes a machine with a large rotating steel drum equipped with tungsten carbide teeth that scrape coal from the seam. Operating in a “room and pillar” (also known as “bord and pillar”) system—where the mine is divided into a series of 20-to-30 foot “rooms” or work areas cut into the coalbed—it can mine as much as five tons of coal a minute, more than a non-mechanised miner of the 1920s would produce in an entire day. Continuous miners account for about 45% of underground coal production. Conveyors transport the removed coal from the seam. Remote-controlled continuous miners are used to work in a variety of difficult seams and conditions, and robotic versions controlled by computers are becoming increasingly common.
  • Blast mining is an older practice that uses explosives such as dynamite to break up the coal seam, after which the coal is gathered and loaded on to shuttle cars or conveyors for removal to a central loading area. This process consists of a series of operations that begins with “cutting” the coalbed so it will break easily when blasted with explosives. This type of mining accounts for less than 5% of total underground production in the U.S. today.
  • Starwall mining, a method currently accounting for less than 1% of deep coal production, involves the use of a continuous mining machine with moveable roof supports, similar to longwall. The continuous miner shears coal panels 150-200 feet wide and more than a half-mile long, having regard to factors such as geological strata.
  • Retreat mining is a method in which the ceiling of the mine is held up by wooden beams. The beams are removed, allowing the ceiling to collapse so miners can reach the coal. This is one of the most dangerous forms of mining owing to imperfect predictability of when the ceiling will collapse and possibly crush or trap workers in the mine.

Sunday, September 21, 2008

Modern surface mining

Modern surface mining
Trucks loaded with coal at the Cerrejón coal mine in Colombia.When coal seams are near the surface, it may be economical to extract the coal using open cut (also referred to as open cast or open pit) mining methods. Typically, for coal, strip mining is used. Strip mining exposes the coal by the advancement of an open pit or strip. The earth above the coal seam(s) is known as overburden. A strip of overburden next to the previously mined strip is usually drilled. The drill holes are filled with explosives and blasted. The overburden is then removed using large earthmoving equipment such as draglines, shovel and trucks, excavator and trucks, or bucket-wheels and conveyors. This overburden is put into the previously mined (and now empty) strip. When all the overburden is removed, the underlying coal seam will be exposed as a strip known as a 'block'. This 'block' of coal may be drilled and blasted (if hard) or otherwise loaded on to trucks or conveyors for transport to the coal preparation (or wash) plant. Once this strip is empty of coal, the process is repeated with a new strip being created next to it.

Open cast coal mining recovers a greater proportion of the coal deposit than underground methods, as more of the coal seams in the strata may be exploited. Opencast coal mines can cover many square kilometers.

Most open cast mines in the United States extract bituminous coal. In South Wales open casting for steam coal and anthracite is practiced. In Australia and South Africa open cast mining is used for both thermal and metallurgical coals. Surface mining accounts for around 80% of production in Australia, while in the USA it is used for about 67% of production. Globally, about 40% of coal production involves surface mining.

Mountaintop removal is a form of surface mining that takes place at the topmost portion of a mountain, and is a technique that is commonly applied in Appalachia in the United States. Utilized for the past 30 years, mountaintop mining involves removing the highest part of the mountain for the maximum recovery of coal. The process is highly controversial for the drastic changes in topography, the practice of hollow fills, or filling in valleys with mining debris, and for covering streams and disrupting ecosystems.

Monday, September 15, 2008

Coal Mine

Coal mining

Coal mining is the extraction or removal of coal from the earth by mining. When coal is used for fuel in power generation it is referred to as steaming or thermal coal. Coal that is used to create coke for steel manufacturing is referred to as coking or metallurgical coal. In the United States, UK, and South Africa, a coal mine and its accompanying structures are collectively known as a colliery. In Australia, 'colliery' usually only refers to an underground coal mine.

The oldest continuously worked deep-mine in the UK and possibly the world is Tower Colliery at the northern end of the South Wales valleys in the heart of the South Wales coalfield. This colliery was started in 1805 and at the end of the 20th century it was bought out by its miners rather than being allowed to be closed. Tower Colliery was finally closed on the 25th January 2008.
The World Championships in coal-carrying take place every Easter Monday, at Ossett, West Yorkshire, UK. The race starts from the site of the old Savile & Shaw Cross colliery.
The first commercial coal mines in the United States were started in 1748 in Midlothian, Virginia, near Richmond, Virginia.
In the 1880s, Coal-cutting machines became available (prior to that, coal was mined underground by hand using a pick and shovel.)
By 1912, surface mining was underway with steam shovels specifically designed for coal mining.
Methods of extraction

The most economical method of coal extraction from coal seams depends on the depth and quality of the seams, and also the geology and environmental factors of the area being mined. Coal mining processes are generally differentiated by whether they operate on the surface or underground. Many coals extracted from both surface and underground mines require washing in a coal preparation plant.

Modern surface mining

Trucks loaded with coal at the Cerrejón coal mine in Colombia.When coal seams are near the surface, it may be economical to extract the coal using open cut (also referred to as open cast or open pit) mining methods. Typically, for coal, strip mining is used. Strip mining exposes the coal by the advancement of an open pit or strip. The earth above the coal seam(s) is known as overburden. A strip of overburden next to the previously mined strip is usually drilled. The drill holes are filled with explosives and blasted. The overburden is then removed using large earthmoving equipment such as draglines, shovel and trucks, excavator and trucks, or bucket-wheels and conveyors. This overburden is put into the previously mined (and now empty) strip. When all the overburden is removed, the underlying coal seam will be exposed as a strip known as a 'block'. This 'block' of coal may be drilled and blasted (if hard) or otherwise loaded on to trucks or conveyors for transport to the coal preparation (or wash) plant. Once this strip is empty of coal, the process is repeated with a new strip being created next to it.
Open cast coal mining recovers a greater proportion of the coal deposit than underground methods, as more of the coal seams in the strata may be exploited. Opencast coal mines can cover many square kilometers.
Most open cast mines in the United States extract bituminous coal. In South Wales open casting for steam coal and anthracite is practiced. In Australia and South Africa open cast mining is used for both thermal and metallurgical coals. Surface mining accounts for around 80% of production in Australia, while in the USA it is used for about 67% of production. Globally, about 40% of coal production involves surface mining.
Mountaintop removal is a form of surface mining that takes place at the topmost portion of a mountain, and is a technique that is commonly applied in Appalachia in the United States. Utilized for the past 30 years, mountaintop mining involves removing the highest part of the mountain for the maximum recovery of coal. The process is highly controversial for the drastic changes in topography, the practice of hollow fills, or filling in valleys with mining debris, and for covering streams and disrupting ecosystems.

Saturday, September 6, 2008

Wildlife photography

Wildlife photography

Wildlife photography is the act of taking photographs of wildlife. Wildlife photography is regarded as being one of the more challenging forms of photography.

Requirements are:
  • a technically sound photographer, such as being able to expose correctly.

  • advanced photographic equipment. While wildlife photographs can be taken using basic equipment it is made easier with advanced equipment. For example, 600mm lenses in conjunction with the latest autofocus camera bodies are generally required for bird photography. As an alternative, less expensive superzoom bridge cameras (with equivalent focal lengths exceeding 500mm, 800mm+ with a teleconverter) can produce excellent results, despite being far less expensive and more portable than a SLR body with a supertelephoto lens. Due to their small sensors these cameras are limited to ISO 100 to achieve optimum image quality which can be a hindrance with fast moving animals or in less than ideal lighting situations (dawn or dusk).

  • Good field craft skills. Wildlife is usually difficult to approach thus a knowledge of the animal's behaviour is needed in order to be able to predict actions. An ability to stalk animals is often also required. Hides may be required when photographing more timid subjects as these conceal the photographer.

Sunday, August 31, 2008

Nature-Macro / Texture

Macro / Texture

The macro photography article explains close-up photography in general; however, this is also a type of nature photography. While common macro subjects - bees, dragonflies, and so on - could be described as wildlife, their world also makes for good photography.
Many photographers record images of the texture in a stone, tree bark, leaf, or any of other small scenes. Many of these images are abstract. Tiny plants and mushrooms are also popular subjects. Close-up nature photography doesn't always need a true macro lens; however, the scenes here are small enough that they're generally considered different from regular landscapes.

Use of Color

The presence (or absence) of color is not a requirement of nature photography. More black and white photos are being produced by digital means today than on film in the 1930s.
Ansel Adams is famous for his black and white depictions of nature, which are still held in high regard today. Galen Rowell praised Fuji Velvia film for its bright, saturated colors, asking "Who wants to take dull pictures that will last a hundred years?" Both men distinguish between photography as an expressive art form and sensitometry; an accurate reproduction is not necessary.


A number of ethical concerns and debates surround the creation of nature photography. Common issues involve the potential of stress or harm to wildlife, the potential of photographers overrunning and destroying natural areas, the use of game farms, and veracity and manipulation in photography.

Sunday, August 24, 2008

Nature photography

Nature photography

Nature photography refers to a wide range of photography taken outdoors and devoted to displaying natural elements such as landscapes, wildlife, plants, and close-ups of natural scenes and textures. Nature photography tends to put a stronger emphasis on the aesthetic value of the photo than other photography genres, such as photojournalism and documentary photography.
Nature photographs are published in scientific, travel and cultural magazines such as National Geographic Magazine and Audubon Magazine or other more specific magazines such as Outdoor Photographer and Nature's Best Photography.

Landscape Photography

Landscape photography, also known as Landscape art, is a genre meant to show the beauty of the natural world. Most landscape photographers strive to show as little human activity as possible, ideally none, in their photos. Instead, the subjects are landforms, weather, and ambient light.
Waterfalls are especially popular, as are mountain vistas. These often call for neutral density or polarizing filters.
Landscapes are most often created with a wide angle lens (24 mm and 35 mm are especially popular) and a tripod. Small apertures (f/11 to f/22) are used to maximize depth of field. Many photographers use medium or large format systems to record as much detail as possible, although the vast majority of landscapes shot today are from digital SLRs and compact cameras.
Landscape photography has become a valuable tool to inspire environmental stewardship. Capturing the beauty of unspoiled places serves to bring dwindling wilderness areas into the public eye. Many noted landscape photographers provide images to environmental protection organizations. Noted organizations use professional and amateur photographers' work to further the preservation cause.

Wildlife Photography

Wildlife photography is devoted to capturing interesting animals in action, such as eating, fighting, or in flight. Although usually shot in the wild, game farms are also a frequent location for wildlife photography.
The techniques of wildlife photography differ greatly from those used in landscape photography. For example, in wildlife photography wide apertures are used to achieve a fast shutter speed, freeze the subject's motion, and blur the backgrounds, while landscape photographers prefer small apertures. Wildlife is also usually shot with long telephoto lenses from a great distance; the use of such telephoto lenses frequently necessitates the use of a tripod (since the longer the lens, the harder it is to handhold). Many wildlife photographers use blinds or camouflage.

Saturday, August 16, 2008

Photography as an art form

Photography as an art form
During the twentieth century, both fine art photography and documentary photography became accepted by the English-speaking art world and the gallery system. In the United States, a handful of photographers, including Alfred Stieglitz, Edward Steichen, John Szarkowski, and Edward Weston, spent their lives advocating for photography as a fine art. At first, fine art photographers tried to imitate painting styles. This movement is called Pictorialism, often using soft focus for a dreamy, 'romantic' look. In reaction to that, Weston, Ansel Adams, and others formed the f/64 Group to advocate 'straight photography', the photograph as a (sharply focused) thing in itself and not an imitation of something else.

The aesthetics of photography is a matter that continues to be discussed regularly, especially in artistic circles. Many artists argued that photography was the mechanical reproduction of an image. If photography is authentically art, then photography in the context of art would need redefinition, such as determining what component of a photograph makes it beautiful to the viewer. The controversy began with the earliest images "written with light"; Nicéphore Niépce, Louis Daguerre, and others among the very earliest photographers were met with acclaim, but some questioned if their work met the definitions and purposes of art.
Clive Bell in his classic essay Art states that only "significant form" can distinguish art from what is not art.
“ There must be some one quality without which a work of art cannot exist; possessing which, in the least degree, no work is altogether worthless. What is this quality? What quality is shared by all objects that provoke our aesthetic emotions? What quality is common to Sta. Sophia and the windows at Chartres, Mexican sculpture, a Persian bowl, Chinese carpets, Giotto's frescoes at Padua, and the masterpieces of Poussin, Piero della Francesca, and Cezanne? Only one answer seems possible - significant form. In each, lines and colors combined in a particular way, certain forms and relations of forms, stir our aesthetic emotions. ”
On February 14th 2006 Sotheby’s London sold the 2001 photograph "99 Cent II Diptychon" for an unprecedented $3,346,456 to an anonymous bidder making it the most expensive of all time.
Technical photography
The camera has a long and distinguished history as a means of recording phenomena from the first use by Daguerre and Fox-Talbot, such as astronomical events (eclipses for example) and small creatures when the camera was attached to the eyepiece of microscopes (in photomicroscopy). The camera also proved useful in recording crime scenes and the scenes of accidents, one of the first uses being at the scene of the Tay Rail Bridge disaster of 1879. The set of accident photographs was used in the subsequent court of inquiry so that witnesses could identify pieces of the wreckage, and the technique is now commonplace in courts of law.
Between 1846 and 1852 Charles Brooke invented a technology for the automatic registration of instruments by photography. These instruments included barometers, thermometers, psychrometers, and magnetometers, which recorded their readings by means of an automated photographic process.

Other photographic image forming techniques
Besides the camera, other methods of forming images with light are available. For instance, a photocopy or xerography machine forms permanent images but uses the transfer of static electrical charges rather than photographic film, hence the term electrophotography. Photograms are images produced by the shadows of objects cast on the photographic paper, without the use of a camera. Objects can also be placed directly on the glass of an image scanner to produce digital pictures

Monday, August 11, 2008

Photography styles
Commercial photography
Manual shutter control and exposure settings can achieve unusual resultsCommercial photography is probably best defined as any photography to which money exchanges hands. In this light money could be paid for the subject of the photograph or the photograph itself. Wholesale, retail, and professional uses of photography would fall under this definition. The commercial photographic world could include:
  • Advertising photography: photographs made to illustrate and usually sell a service or product. These images are generally done with an advertising agency, design firm or with an in-house corporate design team.
  • Fashion and glamour photography: This type of photography usually incorporates models. Fashion photography emphasizes the clothes or product, glamour emphasizes the model. Glamour photography is popular in advertising and in men's magazines. Models in glamour photography may be nude, but this is not always the case.
  • Crime Scene Photography: This type of photography consists of photographing scenes of crime such as robberies and murders. A black and white camera or an infrared camera may be used to capture specific details.
  • Still life photography usually depicts inanimate subject matter, typically commonplace objects which may be either natural or man-made. Food photography can be used for editorial, packaging or advertising use.
  • Food photography is similar to still life photography, but requires some special skills.
  • Editorial photography: photographs made to illustrate a story or idea within the context of a magazine. These are usually assigned by the magazine.
  • Photojournalism: this can be considered a subset of editorial photography. Photographs made in this context are accepted as a documentation of a news story.
  • Portrait and wedding photography: photographs made and sold directly to the end user of the images.
  • Fine art photography: photographs made to fulfill a vision, and reproduced to be sold directly to the customer. Landscape photography: photographs of different locations made to be sold to tourists as postcards
  • Conceptual photography: Photography that turns a concept or idea into a photograph. Even though what is depicted in the photographs are real objects, the subject is strictly abstract. Wildlife photography that demonstrates life of the animals.
  • Pornography: explicit depiction of sexual subject matter, especially with the sole intention of sexually exciting the viewer using a variety of media including photography. See History of erotic photography.
  • Photo sharing: publishing or transfer of a user's digital photos online.
The market for photographic services demonstrates the aphorism "one picture is worth a thousand words," which has an interesting basis in the history of photography. Magazines and newspapers, companies putting up Web sites, advertising agencies and other groups pay for photography.
Many people take photographs for self-fulfillment or for commercial purposes. Organizations with a budget and a need for photography have several options: they can employ a photographer directly, organize a public competition, or obtain rights to stock photographs. Photo stock can be procured through traditional stock giants, such as Getty Images or Corbis; smaller microstock agencies, such as Fotolia; or web marketplaces, such as Cutcaster.

Tuesday, August 5, 2008

Digital photography

Digital photography

Traditional photography burdened photographers working at remote locations without easy access to processing facilities, and competition from television pressured photographers to deliver images to newspapers with greater speed. Photo journalists at remote locations often carried miniature photo labs and a means of transmitting images through telephone lines. In 1981, Sony unveiled the first consumer camera to use a charge-coupled device for imaging, eliminating the need for film: the Sony Mavica. While the Mavica saved images to disk, the images were displayed on television, and the camera was not fully digital. In 1990, Kodak unveiled the DCS 100, the first commercially available digital camera. Although its high cost precluded uses other than photojournalism and professional photography, commercial digital photography was born.

Digital imaging uses an electronic image sensor to record the image as a set of electronic data rather than as chemical changes on film. The primary difference between digital and chemical photography is that chemical photography resists manipulation because it involves film and photographic paper, while digital imaging is a highly manipulative medium. This difference allows for a degree of image post-processing that is comparatively difficult in film-based photography and permits different communicative potentials and applications.

Digital point-and-shoot cameras have become widespread consumer products, outselling film cameras, and including new features such as video and audio recording. Kodak announced in January 2004 that it would no longer sell reloadable 35 mm cameras in western Europe, Canada and the United States after the end of that year. Kodak was at that time a minor player in the reloadable film cameras market. In January 2006, Nikon followed suit and announced that they will stop the production of all but two models of their film cameras: the low-end Nikon FM10, and the high-end Nikon F6. On May 25, 2006, Canon announced they will stop developing new film SLR cameras.

According to a survey made by Kodak in 2007, 75 percent of professional photographers say they will continue to use film, even though some embrace digital.
According to the U.S. survey results, more than two-thirds (68 percent) of professional photographers prefer the results of film to those of digital for certain applications including:
  • film’s superiority in capturing more information on medium and large format films (48 percent); creating a traditional photographic look (48 percent);
  • capturing shadow and highlighting details (45 percent);
  • the wide exposure latitude of film (42 percent);
  • and archival storage (38 percent)
Because photography is popularly synonymous with truth ("The camera doesn't lie."), digital imaging has raised many ethical concerns. Many photojournalists have declared they will not crop their pictures, or are forbidden from combining elements of multiple photos to make "illustrations," passing them as real photographs. Many courts will not accept digital images as evidence because of their inherently manipulative nature. Today's technology has made picture editing relatively simple for even the novice photographer.

Wednesday, July 30, 2008

Photography types

Photography types

Black-and-white photography

All photography was originally monochrome, most of these photographs were black-and-white. Even after color film was readily available, black-and-white photography continued to dominate for decades, due to its lower cost and its "classic" photographic look. It is important to note that some monochromatic pictures are not always pure blacks and whites, but also contain other hues depending on the process. The Cyanotype process produces an image of blue and white for example. The albumen process which was used more then 150 years ago had brown tones.

Many photographers continue to produce some monochrome images. Some full color digital images are processed using a variety of techniques to create black and whites, and some cameras have even been produced to exclusively shoot monochrome.

Color photography
Color photography was explored beginning in the mid 1800s. Early experiments in color could not fix the photograph and prevent the color from fading. The first permanent color photo was taken in 1861 by the physicist James Clerk Maxwell.
One of the early methods of taking color photos was to use three cameras. Each camera would have a color filter in front of the lens. This technique provides the photographer with the three basic channels required to recreate a color image in a darkroom or processing plant. Russian photographer Sergei Mikhailovich Prokudin-Gorskii developed another technique, with three color plates taken in quick succession.
Practical application of the technique was held back by the very limited color response of early film; however, in the early 1900s, following the work of photo-chemists such as H. W. Vogel, emulsions with adequate sensitivity to green and red light at last became available.
The first color plate, Autochrome, invented by the French Lumière brothers, reached the market in 1907. It was based on a 'screen-plate' filter made of dyed dots of potato starch, and was the only color film on the market until German Agfa introduced the similar Agfacolor in 1932. In 1935, American Kodak introduced the first modern ('integrated tri-pack') color film, Kodachrome, based on three colored emulsions. This was followed in 1936 by Agfa's Agfacolor Neue. Unlike the Kodachrome tri-pack process, the color couplers in Agfacolor Neue were integral with the emulsion layers, which greatly simplified the film processing. Most modern color films, except Kodachrome, are based on the Agfacolor Neue technology. Instant color film was introduced by Polaroid in 1963.
Color photography may form images as a positive transparency, intended for use in a slide projector or as color negatives, intended for use in creating positive color enlargements on specially coated paper. The latter is now the most common form of film (non-digital) color photography owing to the introduction of automated photoprinting equipment.

Friday, July 25, 2008

History of photography

History of photography
Photography is the result of combining several technical discoveries. Long before the first photographs were made, Ibn al-Haytham (Alhazen) (965–1040) invented the camera obscura and pinhole camera, Albertus Magnus (1193–1280) discovered silver nitrate, and Georges Fabricius (1516–1571) discovered silver chloride. Daniel Barbaro described a diaphragm in 1568. Wilhelm Homberg described how light darkened some chemicals (photochemical effect) in 1694. The fiction book Giphantie, by French author Tiphaigne de la Roche, described what can be interpreted as photography.

Photography as a usable process goes back to the 1820s with the development of chemical photography. The first permanent photograph was an image produced in 1826 by the French inventor Nicéphore Niépce. However, the picture took eight hours to expose, so he went about trying to find a new process. Working in conjunction with Louis Daguerre, they experimented with silver compounds based on a Johann Heinrich Schultz discovery in 1724 that a silver and chalk mixture darkens when exposed to light. Niépce died in 1833, but Daguerre continued the work, eventually culminating with the development of the daguerreotype in 1837. Eventually, France agreed to pay Daguerre a pension for his formula, in exchange for his promise to announce his discovery to the world as the gift of France, which he did in 1839.

Meanwhile, Hercules Florence had already created a very similar process in 1832, naming it Photographie, and William Fox Talbot had earlier discovered another means to fix a silver process image but had kept it secret. After reading about Daguerre's invention, Talbot refined his process so that it might be fast enough to take photographs of people. By 1840, Talbot had invented the calotype process, which creates negative images. John Herschel made many contributions to the new methods. He invented the cyanotype process, now familiar as the "blueprint". He was the first to use the terms "photography", "negative" and "positive". He discovered sodium thiosulphate solution to be a solvent of silver halides in 1819, and informed Talbot and Daguerre of his discovery in 1839 that it could be used to "fix" pictures and make them permanent. He made the first glass negative in late 1839.

In March of 1851, Frederick Scott Archer published his findings in "The Chemist" on the wet plate collodion process. This became the most widely used process between 1852 and the late 1880s when the dry plate was introduced. There are three subsets to the Collodion process; the Ambrotype (positive image on glass), the Ferrotype or Tintype (positive image on metal) and the negative which was printed on Albumen or Salt paper.

Many advances in photographic glass plates and printing were made in through the nineteenth century. In 1884, George Eastman developed the technology of film to replace photographic plates, leading to the technology used by film cameras today.

Sunday, July 20, 2008

Controllong ...

Controlling the photographic exposure and rendering
Camera controls are inter-related. The total amount of light reaching the film plane (the "exposure") changes with the duration of exposure, aperture of the lens, and focal length of the lens (which changes as the lens is zoomed). Changing any of these controls alters the exposure. Many cameras may be set to adjust most or all of these controls automatically. This automatic functionality is useful in many situations, and in most situations to occasional photographers.

The duration of an exposure is referred to as shutter speed, often even in cameras that don't have a physical shutter, and is typically measured in fractions of a second. Aperture is expressed by an f-number or f-stop (derived from focal ratio), which is proportional to the ratio of the focal length to the diameter of the aperture. If the f-number is decreased by a factor of , the aperture diameter is increased by the same factor, and its area is increased by a factor of 2. The f-stops that might be found on a typical lens include 2.8, 4, 5.6, 8, 11, 16, 22, 32, where going up "one stop" (using lower f-stop numbers) doubles the amount of light reaching the film, and stopping down one stop halves the amount of light.

Exposures can be achieved through various combinations of shutter speed and aperture. For example, f/8 at 8 ms (=1/125th of a second) and f/5.6 at 4 ms (=1/250th of a second) yield the same amount of light. The chosen combination has an impact on the final result. In addition to the subject or camera movement that might vary depending on the shutter speed, the aperture (and focal length of the lens) determine the depth of field, which refers to the range of distances from the lens that will be in focus. For example, using a long lens and a large aperture (f/2.8, for example), a subject's eyes might be in sharp focus, but not the tip of the nose. With a smaller aperture (f/22), or a shorter lens, both the subject's eyes and nose can be in focus. With very small apertures, such as pinholes, a wide range of distance can be brought into focus.

Image capture is only part of the image forming process. Regardless of material, some process must be employed to render the latent image captured by the camera into the final photographic work. This process consists of two steps, development, and printing.

During the printing process, modifications can be made to the print by several controls. Many of these controls are similar to controls during image capture, while some are exclusive to the printing process. Most controls have equivalent digital concepts, but some create different effects. For example, dodging and burning controls are different between digital and film processes. Other printing modifications include:
  • Chemicals and process used during film development
  • Duration of exposure – equivalent to shutter speed
  • Printing aperture – equivalent to aperture, but has no effect on depth of field
  • Contrast
  • Dodging – reduces exposure of certain print areas, resulting in lighter areas
  • Burning – increases exposure of certain areas, resulting in darker areas
  • Paper texture – glossy, matte, etc
  • Paper type – resin-coated (RC) or fiber-based (FB)
  • Paper size
  • Toners – used to add warm to cool tones to black and white
Uses of photography
Photography gained the interest of many scientists and artists from its inception. Scientists have used photography to record and study movements, such as Eadweard Muybridge's study of human and animal locomotion in 1887. Artists are equally interested by these aspects but also try to explore avenues other than the photo-mechanical representation of reality, such as the pictorialist movement. Military, police, and security forces use photography for surveillance, recognition and data storage. Photography is used to preserve memories of favorite times, to capture special moments, to tell stories, to send messages, and as a source of entertainment.
Commercial advertising relies heavily on photography and has contributed greatly to its development.

Sunday, July 13, 2008


Photography (IPA: [fә'tɒgrәfi] or IPA: [fә'tɑːgrәfi]) is the process of recording pictures by means of capturing light on a light-sensitive medium, such as a film or electronic sensor. Light patterns reflected or emitted from objects expose a sensitive silver halide based chemical or electronic medium during a timed exposure, usually through a photographic lens in a device known as a camera that also stores the resulting information chemically or electronically. Photography has many uses for both business and pleasure. It is often the basis of advertising and in fashion print. Photography can also be viewed as a commercial and artistic endeavor. A modern DSLR camera, the Canon EOS 40DThe word "photography" comes from the French photographie which is based on the Greek φώς (phos) "light" + γραφίς (graphis) "stylus", "paintbrush" or γραφή (graphê) "representation by means of lines" or "drawing", together meaning "drawing with light." Traditionally, the product of photography has been called a photograph, commonly shortened to photo.
Photographic cameras
The camera or camera obscura is the image-forming device, and photographic film or a silicon electronic image sensor is the sensing medium. The respective recording medium can be the film itself, or a digital electronic or magnetic memory.
Photographers control the camera and lens to "expose" the light recording material (such as film) to the required amount of light to form a "latent image" (on film) or "raw file" (in digital cameras) which, after appropriate processing, is converted to a usable image. Modern digital cameras replace film with an electronic image sensor based on light-sensitive electronics such as charge-coupled device (CCD) or complementary metal-oxide-semiconductor (CMOS) technology. The resulting digital image is stored electronically, but can be reproduced on paper or film.
The controls usually include but are not limited to the following:
Focus of the lens Aperture of the lens – adjustment of the iris, measured as f-number, which controls the amount of light entering the lens. Aperture also has an effect on focus and depth of field, namely, the smaller the opening [aperture], the less light but the greater the depth of field--that is, the greater the range within which objects appear to be sharply focused. Shutter speed – adjustment of the speed (often expressed either as fractions of seconds or as an angle, with mechanical shutters) of the shutter to control the amount of time during which the imaging medium is exposed to light for each exposure. Shutter speed may be used to control the amount of light striking the image plane; 'faster' shutter speeds (that is, those of shorter duration) decrease both the amount of light and the amount of image blurring from subject motion or camera motion. White balance – on digital cameras, electronic compensation for the color temperature associated with a given set of lighting conditions, ensuring that white light is registered as such on the imaging chip and therefore that the colors in the frame will appear natural. On mechanical, film-based cameras, this function is served by the operator's choice of film stock. In addition to using white balance to register natural coloration of the image, photographers may employ white balance to aesthetic end, for example white balancing to a blue object in order to obtain a warm color temperature. Metering – measurement of exposure at a midtone so that highlights and shadows are exposed according to the photographer's wishes. Many modern cameras feature this ability, though it is traditionally accomplished with the use of a separate light metering device. ISO speed – traditionally used to set the film speed of the selected film on film cameras, ISO speeds are employed on modern digital cameras as an indication of the system's gain from light to numerical output and to control the automatic exposure system. A correct combination of ISO speed, aperture, and shutter speed leads to an image that is neither too dark nor too light. Auto-focus point – on some cameras, the selection of a point in the imaging frame upon which the auto-focus system will attempt to focus. Many Single-lens reflex cameras (SLR) feature multiple auto-focus points in the viewfinder. Many other elements of the imaging device itself may have a pronounced effect on the quality and/or aesthetic effect of a given photograph; among them are:
Focal length and type of lens (telephoto or "long" lens, macro, wide angle, fisheye, or zoom) Filters or scrims placed between the subject and the light recording material, either in front of or behind the lens Inherent sensitivity of the medium to light intensity and color/wavelengths. The nature of the light recording material, for example its resolution as measured in pixels or grains of silver halide.