Category: Define

Air Mass An extensive body of air throughout which the horizontal temperature and moisture characteristics are similar. Air This is considered the mixture of gases

Albedo The ratio of the amount of radiation reflected from an object’s surface compared to the amount that strikes it. This varies according to the

Altimeter An instrument used to determine the altitude of an object with respect to a fixed level. The type normally used by meteorologists measures the

Altitude In meteorology, the measure of a height of an airborne object in respect to a constant pressure surface or above mean sea level. Meteorology

Altocumulus Composed of flattened, thick, gray, globular masses, this middle cloud genus is primarily made of water droplets. In the mid-latitudes, cloud bases are usually

Altostratus This middle cloud genus is composed of water droplets, and sometimes ice crystals, In the mid-latitudes, cloud bases are generally found between 15,000 and

Anemometer An instrument that measures the speed or force of the wind. Wind Speed The rate of the motion of the air on a unit

Anticyclone A relative pressure maximum. An area of pressure that has diverging winds and a rotation opposite to the earth’s rotation. This is clockwise the

Anvil The upper portion of a cumulonimbus cloud that becomes flat and spread-out, sometimes for hundreds of miles downstream from the parent cloud. It may

Aphelion The point on the earth’s orbit that is farthest from the sun. Although the position is part of a 21,000 year cycle, currently it