| A | B |
|---|
| weather | the short term state of the atmosphere; includes temperature, humidity, precipitation, wind, and visibility |
| humidity | the amount of water vapor in the air |
| relative humidity | the ratio of the amount of water in the air and the maximum amount that the air can hold at a given temperature |
| condensation | occurs when water vapor cools and changes from a gas to a liquid; formation of clouds |
| evaporation | occurs when liquid water changes to water vapor ( a gas) |
| precipitation | occurs when rain, snow, sleet, or hail falls from the clouds to the Eath's surface |
| runoff | water in the form of precipitation that flows across land and collects in streams, rivers, and other bodies of water, including the ocean |
| water cycle | the continuous movement of the water on Earth |
| psychrometer | instrument that can be used to measure the relative humidity |
| dew point | the temperature at which a gas condenses to a liquid; air is saturated at this point |
| cloud | collection of water droplets |
| cumulus clouds | puffy white clouds with flat bottoms; form whne warm air rises |
| cumulonimbus clouds | the clouds that form thunderstorms |
| status clouds | form in layers; cover large areas of the sky and block out the sun |
| nimbostratus clouds | dark, layered clouds that form a long, continuous rain |
| fog | a stratus cloud that has formed near the ground |
| cirrus cloud | feathery, whispy cloud formed at high altitudes |
| sleet | formed when rain falls through a layer of freezing air |
| air mass | a large body of air where temperature and moisture content are similar |
| front | the boundary between air masses of different densities and different tempertatures |
| mP | cold, wet air mass |
| cP | dry, cold air mass |
| mT | wet, warm air mass |
| cT | dry, warm air mass |
| source region | area over which an air mass forms |
| cyclone | air masses come together and rise; lower pressure on the inside |
| anticyclone | air moves apart and sinks; higher pressure on the inside |
| thunderstorm | small, intense weather systems that produce strong winds, heavy rain, lightning and thunder |
| lightning | an electric discharge that takes place between to oppositely charged surfaces |
| thunder | the sound caused by the rapid expansion of air around a lightning strike |
| tornado | a destructive, rotating column of air |
| hurricane | large, tropical rotating storm system |
| storm surge | a wall of water that travels over the ocean because of strong winds and low atmospheric pressure |
| thermometer | instrument that measures and indicates temperature |
| barometer | an instrument that measures atmospheric pressure |
| weather forecast | prediction of weather conditions over 3-5 days |
| meterologist | the person who observes and collects data and makes weather predictions |
| anemometer | an instrument used to measure wind speed |
| radar | tool used to find the location, amound, and movement of precipitation |
| station model | a small circle that shows the location of a weather station; symbols and numbers represent weather data |
| isobars | lines on a weather map that connect eaqual areas of pressure |
