| A | B |
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| CLIMATE | long-term average of weather in an area |
| WEATHER | day-to-day changes in atmospheric conditions, including temperature, air pressure, humidity, wind, cloud coverage, or precipitation |
| 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 |
| ANEMOMETER | tool that measures wind speed |
| BAROMETER | tool that measures air pressure |
| WIND VANE | tool that measures wind direction |
| 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 |
| CORIOLIS EFFECT | the change that Earth's rotation causes in the motion of objects and that explains how winds curve |
| 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 |
| WATER CYCLE | the continual movement of water among Earth's atmosphere, oceans, and land surface through evaporation, condensation, and precipitation |
| 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. |
| WESTERLIES | The dominant winds that move across the USA |
| POLAR | dry, cold climate zone above 60 degree latitude |
| TEMPERATE | seasonably variable climate zone between 40 and 60 degrees latitude, north or south of the equator |
| TROPICAL | warm, moist climate zone near the equator |
| RELATIVE HUMIDITY | a percentage of the maximum amount of water vapor the air can hold at its current temperature |
| TEMPERATURE | Measure of how hot or cold the air is. The closer to the equator you are, the warmer the temperature. Oceans and elevation also affect temperature. |
| WEATHER | includes temperature, precipitation, air pressure, wind and clouds. Powered by energy from the Sun and it is highly changeable. It changes from place to place and from hour to hour. |
| WIND | movement of air from on place to another. It is caused by differences in air pressure. Air flows from areas of high pressure to areas of low pressure. The greater the differences in air pressure the faster the wind. |
| CLOUDS | tiny visible water droplets of ice crystals high in the air |
| ISOTHERM | line on the map joining up all the places with the same temperature. |
| 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. |
