ARCHIVE: e-Digest Statistics about: Ozone Depletion
- dispersion aerosols are formed when minute particles are ground down from solids or atomised from liquids. Air currents and vibration can then transfer them into a state of suspension. Condensation aerosols form when supersaturated vapours condense, or when two gases react to form a product which is solid at normal temperatures. They are easily suspended in the air to become widely dispersed.
- Carbon dioxide
- CO2 a colourless, odourless gas which is a natural constituent of air. Formed by natural processes and by the combustion of fuels containing carbon. A greenhouse gas.
- Carbon tetrachloride
- CCl4 a colourless, toxic liquid that is the most important halide of carbon. Its main use has been as an industrial solvent and as a component of the extinguishant in fire extinguishers.
- CFCs (Chlorofluorocarbons)
- compounds of carbon, fluorine and chlorine widely used in aerosols and as refrigerants, solvents and cleaning fluids. They are chemically inert and so have atmospheric lifetimes of over 50 years. They are also important greenhouse gases.
- general term for CFCs, HCFCs and other similar compounds.
- HCFCs (hydrochlorofluorocarbons)
- organic compounds of carbon, hydrogen, chlorine and fluorine. Being developed as replacements for CFCs as the hydrogen atoms make them less liable to chemical attack in the troposphere giving them much shorter lifetimes. They are also greenhouse gases.
- HFCs (hydrofluorocarbons)
- compounds consisting of hydrogen, fluorine, and carbon atoms which, like the HCFCs, are destroyed naturally in the lower atmosphere. They have many of the useful properties of the CFCs. They are important greenhouse gases with very high global warming potential, but because they do not contain chlorine, they are not involved in ozone depletion.
- Infrared radiation lies between the visible and microwave portions of the electromagnetic spectrum. The primary source is heat or thermal radiation. Any object which has a temperature i.e. anything above absolute zero (-459.67 degrees Fahrenheit or -273.15 degrees Celsius or 0 (zero) Kelvin), radiates in the infrared.
- CH4 is a light, colourless and odourless gaseous hydrocarbon. Formed during the decomposition of organic matter. It is the main constituent of most natural gas and is a greenhouse gas.
- Methyl chloroform
- a halocarbon with a lifetime of 6 years used as a solvent and cleaning fluid.
- Nitrous oxide
- N2O, a relatively inert oxide of nitrogen emitted by soils and during the manufacture of nylon. It is a greenhouse gas.
- PFCs (Perfluorocarbons)
- PFCs, for example tetrafluoromethane (CF4) and hexafluoroethane (C2F6), are greenhouse gases with a very high global warming potential in addition to an exceptionally long atmospheric lifetime.
- Radiative forcing
- enhanced radiative heating of the earth.
- Sulphur hexafluoride is another very potent greenhouse gas with a very high global warming potential.
- natural mechanism by which elements are removed from the atmosphere.
- Troposphere and stratosphere
- the atmosphere is divided into layers that are defined approximately by the distance above the surface of the earth; troposphere 0-15km, stratosphere 15-50km. Each layer has distinct physical and chemical properties.
- Ultraviolet can damage DNA. UV-B light energy can break bonds in DNA. Most of the DNA breakages are repaired by proteins present in the cells nucleus but unrepaired genetic damage of the DNA can lead to skin cancers. The ozone layer protects all life from the deadly ultraviolet rays of the sun.
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Page last modified: 16 September 2003
Page published: 10 September 2003