Free website to learn English: Science and Nature English language terms & their definitions, words beginning with the letter A
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English for Science & Nature Glossary of Terms – A

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acid rain – the precipitation of dilute solutions of strong mineral acids, formed by the mixing in the atmosphere of various industrial pollutants, primarily sulfur dioxide and nitrogen oxides, with naturally occuring oxygen and water vapor.

act – in the legislative sense, a bill or measure passed by the Government; a law.

aerosol – a suspension of small liquid or solid particles in gas.

air pollution – toxic or radioactive gases or particulate matter introduced into the atmosphere, usually as a result of human activity.

alternative energy – energy that is not popularly used and is usually environmentally sound, such as solar or wind energy (as opposed to fossil fuels).

alternative fibers – fibers produced from non-wood sources for use in paper making.

alternative fuels – transportation fuels other than gasoline or diesel. Includes natural gas, methanol, and electricity.

alternative transportation – modes of travel other than private cars, such as walking, bicycling, rollerblading, carpooling and transit.

amendment – a change or addition to an existing law or rule.

ancient forest – a forest that is typically older than 200 years with large trees, dense canopies and an abundance of diverse wildlife.

aquaculture – the controlled rearing of fish or shellfish by people or corporations who own the harvestable product, often involving the capture of the eggs or young of a species from wild sources, followed by rearing more intensively than possible in nature.

aquifer – underground source of water.

arms control – coordinated action based on agreements to limit, regulate, or reduce weapon systems by the parties involved.

ash – incombustible residue left over after incineration or other thermal processes.

asthma – a condition marked by laboured breathing, constriction of the chest, coughing and gasping usually brought on by allergies.

atmosphere – the 500 km thick layer of air surrounding the earth which supports the existence of all flora and fauna.

atomic energy – energy released in nuclear reactions. When a neutron splits an atom’s nucleus into smaller pieces it is called fission. When two nuclei are joined together under millions of degrees of heat it is called fusion.