| A | B |
|---|
| AIR MASS | large body of air with the same temperature and humidity |
| FRONT | where two different air masses meet normally causing precipitation |
| HUMIDITY | amount of moisture in the air |
| JET STREAM | fast moving stream of wind where cold, polar air meets warm air from the equator |
| AIR PRESSURE | the pressure caused by the weight of a column of air pushing down on an area |
| CONDENSATION | the process by which molecules of water vapor in the air become liquid water |
| EVAPORATION | the process by which water molecules in liquid water escape into the air as water vapor |
| PRECIPITATION | any form of water that falls from clouds and reaches Earth's surface |
| DEW POINT | the temperature at which the water vapor in the air becomes saturated and condensation begins |
| COLD FRONT | A front where cold air moves in under a warm air mass. |
| WARM FRONT | Forms when warm air slides up and over a cold air mass; it brings gentle rain or light snow followed by warmer weather. |
| HIGH PRESSURE | A mass of sinking cool air that usually bring fair weather. |
| LOW PRESSURE | A mass of rising warm air air that usually bring stormy weather. |
| CLOUDS | tiny visible water droplets of ice crystals high in the air |
| CIRRUS CLOUDS | the most common of the high clouds. They are composed of ice and are thin, wispy clouds blown in high winds into long streamers |
| CIRROSTRATUS CLOUDS | thin, sheetlike high clouds that often cover the entire sky. They are so thin that the sun and moon can be seen through them. These clouds usually come 12-24 hours before a rain or snow storm. |
| ALTOSTRATUS CLOUDS | gray or blue-gray mid level clouds composed of ice crystals and water droplets. The clouds usually cover the entire sky. These clouds often form ahead of storms with continuous rain or snow. |
| ALTOCUMULUS CLOUDS | mid level clouds that are made of water droplets and appear as gray puffy masses. They usually form in groups. If you see altocumulus clouds on a warm, sticky morning, be prepared to see thunderstorms late in the afternoon. |
| STRATUS CLOUDS | uniform grayish clouds that often cover the entire sky. They resemble fog that doesn't reach the ground. Light mist or drizzle sometimes falls out of these clouds. |
| STRATOCUMULUS CLOUDS | low, puffy and gray. Most form in rows with blue sky visible in between them. |
| CUMULUS CLOUDS | white, puffy clouds that look like pieces of floating cotton. These clouds are often called "fair-weather clouds". The base of each cloud is flat and the top of each cloud has rounded towers. |
| CUMULONIMBUS CLOUDS | thunderstorm clouds. High winds can flatten the top of the cloud into an anvil-like shape. These clouds are associated with heavy rain, snow, hail, lightning and even tornadoes. The anvil usually points in the direction the storm is moving. |
| FOG | a cloud on the ground. It is composed of billions of tiny water droplets floating in the air. |
| CONTRAILS | condensation trails left behind jet aircrafts. These form when hot humid air from jet exhaust mixes with environmental air of low vapor pressure and low temperature. The mixing is a result of turbulence generated by the engine exhaust. |
