Tuesday, November 23, 2010

Carbon Cycle


The carbon cycle is the biogeochemical cycle by which carbon is exchanged among thebiospherepedospheregeospherehydrosphere, and atmosphere of the Earth. It is one of the most important cycles of the earth and allows for carbon to be recycled and reused throughout the biosphere and all of its organisms.[citation needed]
The carbon cycle was initially discovered by Joseph Priestley and Antoine Lavoisier, and popularized by Humphry Davy.[1] It is now usually thought of as including the following major reservoirs of carbon interconnected by pathways of exchange:
  • The atmosphere
  • The terrestrial biosphere, which is usually defined to include fresh water systems and non-living organic material, such as soil carbon.
  • The oceans, including dissolved inorganic carbon and living and non-living marine biota,
  • The sediments including fossil fuels.
  • The Earth's interior, carbon from the Earth's mantle and crust is released to the atmosphere and hydrosphere by volcanoes and geothermal systems.
The annual movements of carbon, the carbon exchanges between reservoirs, occur because of various chemical, physical, geological, and biological processes. The ocean contains the largest active pool of carbon near the surface of the Earth, but the deep ocean part of this pool does not rapidly exchange with the atmosphere in the absence of an external influence, such as a black smoker or an uncontrolled deep-water oil well leak.
The global carbon budget is the balance of the exchanges (incomes and losses) of carbon between the carbon reservoirs or between one specific loop (e.g., atmosphere ↔ biosphere) of the carbon cycle. An examination of the carbon budget of a pool or reservoir can provide information about whether the pool or reservoir is functioning as a source or sink for carbon dioxide.

Thursday, November 18, 2010

Temperature Inversion

a temperature inversion

A temperature inversion is a thin layer of the atmosphere where the decrease in temperature with height is much less than normal (or in extreme cases, the temperature increases with height). An inversion, also called a "stable" air layer, acts like a lid, keeping normal convective overturning of the atmosphere from penetrating through the inversion. This can cause several weather-related effects. One is the trapping of pollutants below the inversion, allowing them to build up. If the sky is very hazy, or is sunsets are very red, there is likely an inversion somewhere in the lower atmosphere. This happens more frequently in high pressure zones, where the gradual sinking of air in the high pressure dome typically causes an inversion to form at the base of a sinking layer of air. Another effect is making clouds spread out and take on a flattened appearance. Still another effect is to prevent thunderstorms from forming. Even in an air mass that is hot and humid in the lowest layers, thunderstorms will be prevented if an inversion is keeping this air from rising. The opposite of a temperature inversion is anunstable air layer.