A - C

A
Absolute humidity The mass of water vapor in a given volume of air. It represents the density of water vapor in the air.
Absolute zero A temperature of -273ºC, -460ºF, or 0ºK. Theoretically, there is no molecular motion at this temperature.
Acclimatization The gradual adjustment of the body to new climatic or other environmental conditions, for example, the adjustment to low levels of oxygen at high altitudes. .
Adiabatic process A process that takes place without a transfer of heat between the system (such as an air parcel) and its surroundings. In an adiabatic process compression always results in warming, and expansion results in cooling.
Albedo The percent of radiation returning from a surface compared to that which strikes it.
Ambient air The air surrounding a cloud, or the air surrounding rising or sinking air parcels.
Ambient temperature Temperature of the surrounding (ambient) air.
Anemometer An instrument designed to measure wind speed.
Atmospheric window A region of the electromagnetic spectrum from 8 to 12 µm where the atmosphere is transparent to radiation.
 

B
Barograph A recording instrument that provides a continuous trace of air pressure variation with time.

Barometer An instrument that measures atmospheric pressure. The two most common barometers are the mercury barometer and the aneroid barometer.

Beaufort scale A scale of wind strength based on visual assessment of the effects of wind on seas and vegetation.
Biofuel A product produced from biomass.Biofuel is considered much cleaner than petrol/diesel alternatives.
Biogeochemical Cycle The cyclic pathway through which chemical elements move from the environment to organisms and back to the environment. These are also known as nutrient cycles.  Biotic Potential or Reroductive Potential It is the inherent capacity of population to increase under optimal conditions.
It is calclated as the mltiple of number of youngw produced at each reproduction and number of reproductions in a given period of time.  
Black body A hypothetical object that absorbs all of the radiation that strikes it. It also emits radiation at a maximum rate for its given temperature.

Blizzard A severe weather condition characterized by low temperatures and strong winds (greater than 32 mi/hr) bearing a great amount of snow. When these conditions continue after the falling snow has ended, it is termed a ground blizzard.

Boyle's law When the temperature is held constant, the pressure and density of an ideal gas are directly proportional.

C
Carrying Capicity A level above whichno major increase in population density occure".
or
"the feeding capicity of an ecosystem to a population of a species under the provided set of conditions".  
Community A group of several species (plant and/or animal) living together with mutual tolerance and beneficial interactions in a natural area is known as Community. 

Cirrocumulus A high cloud that appears as a white patch of cloud without shadows. It consists of very small elements in the form of grains or ripples.

Cirrostratus A high cloud appearing as a whitish veil that may totally cover the sky. Often produces halo phenomena.

Cirrus A high cloud composed of ice crystals in the form of thin, white, featherlike clouds in patches, filaments, or narrow bands.

Climate The accumulation of daily and seasonal weather events over a long period of time. A description of aggregate weather conditions; the sum of all statistical weather information that helps describe a place or region.

Cloud base The lowest portion of a cloud.

Cloudburst Any sudden and heavy rain shower.

Cloud cover The amount of the sky obscured by clouds when observed at a particular location.

Cloud seeding The introduction of artificial substances (usually silver iodide or dry ice) into a cloud for the purpose of either modifying its development or increasing its precipitation.

Cold front The leading edge of a cold air mass.

Condensation Process by which water changes phase from a vapor to a liquid.

Condensation nuclei Small particles in the atmosphere that serve as the core of tiny condensing cloud droplets. These may be dust, salt, or other material.

Conduction The transfer of heat by molecular activity from one substance to another, or through a substance. Transfer is always from warmer to colder regions.

Continental Climate A climate lacking marine influence and characterized by more extreme temperatures than in marine climates: therefore, it has a relatively high annual temperature range for its latitude.

Continental tropical air Warm, dry air mass that forms over the subtropical deserts of the south-western United States.

Convergence An atmospheric condition that exists when the winds cause a horizontal net inflow of air into a specified region.

Coriolis effect A deflective force arising from the rotation of the earth on its axis; affects principally synoptic-scale and global-scale winds. Winds are deflected to the right of the initial direction in the Northern Hemisphere, and to the left in the Southern Hemisphere.

Cumulonimbus An exceptionally dense and vertically developed cloud, often with a top in the shape of an anvil. The cloud is frequently accompanied by heavy showers, lightning, thunder, and sometimes hail. It is also known as a thunderstorm cloud.

Cumulus A cloud in the form of individual, detached domes or towers that are usually dense and well defined. It has a flat base with a bulging upper part that often resembles cauliflower. Cumulus clouds of fair weather are called cumulus humilis. Those that exhibit much vertical growth are called cumulus congestur or towering cumulus.

Cumulus Congestus An upward building convective cloud with vertical development between that of a cumulus cloud and a cumulonimbus.