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  • Glossary
| Last Updated:13/04/2015



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  1. Abiotic:

  2. Non-living chemical and physical factors of the environment

  3. Absorption:

  4. One substance taking in another, either physically or chemically.

  5. Acclimation:

  6. The process of an organism adjusting to chronic change in its environment.

  7. Acid deposition:

  8. The falling of acids and acid-forming compounds from the atmosphere to the earth's surface. Acid deposition is commonly known as acid rain, a term that refers only to wet deposition of droplets of acids and acid-forming compounds. Also called acid rain.

  9. Acid rain:

  10. Rain or other forms of precipitation that is unusually acidic.

  11. Acid solution:

  12. Any water solution that has more hydrogen ions (H+) than hydroxide ions (OH-); any water solution with a pH less than 7.

  13. Active solar heating system:

  14. System that uses solar collectors to capture energy from the sun and store it as heat for space heating and water heating. Liquid or air pumped through the collectors transfers the captured heat to a storage system such as an insulated water tank or rock bed.

  15. Adaptation:

  16. Any genetically controlled structural, physiological, or behavioral characteristic that helps an organism survive and reproduce under a given set of environmental conditions.

  17. Aerographics:

  18. The branch of meteorology that studies and describes atmospheric conditions.

  19. Aerometry:

  20. the science of measuring properties of air.

  21. Age Cohort:

  22. A group of people of similar age.

  23. Age-Dependency Ratio:

  24. The ratio of persons in the ages defined as dependent (under 15 years and over 64 years) to persons in the ages defined as economically productive (15-64 years) in a population.

  25. Age-Sex Structure:

  26. The composition of a population as determined by the number or proportion of males and females in each age category. The age-sex structure of a population is the cumulative result of past trends in fertility, mortality, and migration.

  27. Age-Specific Rate:

  28. Rate obtained for specific age groups (for example, age-specific fertility rate, death rate, marriage rate, illiteracy rate, or school enrollment rate).

  29. Age Structure:

  30. The relative proportion of a population in different age group.

  31. Aging of Population:

  32. A process in which the proportions of adults and elderly increase in a population, while the proportions of children and adolescents decrease. This process results in a rise in the median age of the population. Aging occurs when fertility rates decline while life expectancy remains constant or improves at the older ages.

  33. Air pollution:

  34. One or more chemicals in high enough concentrations in the air to (1) harm humans, other animals, vegetation, or materials or (2) alter climate. Excess heat and noise are also considered forms of air pollution. Such chemicals or physical conditions are called air pollutants. See primary pollutant, secondary pollutant.

  35. Arid Dry:

  36. A desert or other area with an arid climate that has little precipitation.

  37. Adaptation:

  38. a characteristic of an organism that has been favoured by natural selection.

  39. Adaptive radiation:

  40. Closely related species that look very different, as a result of having adapted to widely different ecological niches.

  41. Aerobic:

  42. Requiring air or oxygen; used in reference to decomposition processes that occur in the presence of oxygen.

  43. Aerosols:

  44. Solid or liquid particles suspended within the atmosphere.

  45. Afforestation:

  46. planting new forests on lands that have not been recently forested.

  47. Agroforestry:

  48. An ecologically based farming system, that, through the integration of trees in farms, increases social, environmental and economic benefits to land users.

  49. Albedo:

  50. Reflectance; the ratio of light from the Sun that is reflected by the Earth's surface, to the light received by it.

  51. Annual Population Growth Rate:

  52. The rate at which a population is increasing owing to natural increase and migration - birth rate minus death rate plus or minus migration

  53. Anoxic:

  54. With abnormally low levels of oxygen.

  55. Aquifer:

  56. A bed or layer yielding water for wells and springs etc.; an underground geological formation capable of receiving, storing and transmitting large quantities of water. Aquifer types include: confined (sealed and possibly containing “fossil” water); unconfined (capable of receiving inflow); and Artesian (an aquifer in which the hydraulic pressure will cause the water to rise above the upper confining layer).

  57. Autotroph:

  58. an organism that produces complex organic compounds from simple inorganic molecules using energy from light or inorganic chemical reactions.

  59. Available water capacity:

  60. That proportion of soil water that can be readily absorbed by plant roots.