| A | B |
|---|
| abiotic | Refers to nonliving basic elements and compounds of the environment. |
| ZENITH | The point which is elevated 90 degrees from all points on a given observer's astronomical horizon. |
| ZONAL FLOW | The flow of air along a latitudinal component of existing flow, normally from west to east. |
| ZONAL INDEX | The measure of the strength of the westerly winds of the middle latitudes. It is expressed as the horizontal pressure difference between 35 degrees and 55 degrees latitude, or as the corresponding geostrophic wind. |
| ABSORPTION | The process in which incident radiant energy is retained by a substance. |
| stratosphere: | region between the troposphere and mesosphere, extending from 10 to 30 miles above the Earth's surface. |
| temperature | measure of the quantity of thermal energy in a substance |
| ABYSSAL PLAIN | The flat, gently sloping or nearly level region of the sea floor. |
| sea level | the imaginary line from which sea depth and land elevation are measured. |
| mesosphere | atmospheric layer above the stratosphere (50-85 km altitude). |
| mesopause | the uppermost boundary of the mesosphere with the lowest temperature in the atmosphere. |
| jet stream | high speed air flow in the atmosphere forming air rivers several hundred miles across that generally move west to east and mark the boundary that separates two global air masses with significant differences in temperature. |
| hurricane | tropical storms with winds exceeding 74 mph originating over the North Atlantic and North Pacific oceans near high humidity and light winds |
| frost | water that has condensed at a temperature below the freezing point |
| Ablation | The process of being removed. Snow ablation usually refers to removal by melting |
| Absolute Humidity | The density of water vapor. It is the mass of the water vapor divided by the volume that it occupies. |
| Accretion | Growth of precipitation particles by collision of ice crystals with supercooled liquid droplets which freeze on impact |
| Aneroid barometer | An instrument built around a metal structure that bends with changing air pressure. These changes are recorded on a pointer that moves back and forth across a printed scale. |
| Anemometer | An instrument that measures wind speed. |
| Barber Pole | A thunderstorm updraft with a visual appearance including cloud striations that are curved in a manner similar to the stripes of a barber pole. The structure typically is most pronounced on the leading edge of the updraft, while drier air from the rear flank downdraft often erodes the clouds on the trailing side of the updraft. |
