| A | B |
|---|
| anemometer | an instument used to measure wind speed |
| air mass | a huge body of air that has similar temperature, pressure, and humidity throughout |
| anticyclone | a high-pressure center of dry air |
| air pressure | a force that is the result of the weight of a column of air pushing down on an area |
| barometer | an instrument used to measure changes in air pressure |
| cirrus | wispy, feathery clouds made mostly of ice crystals that form at high levels |
| climate | the average, year-after-year conditions of temperature,precipitation, winds, and clouds in an area |
| condensation | The process by which molecules of water vapor in the air become liquid vapor. |
| conduction | The direct transfer of heat from one substance to another substance that it is touching. |
| continental air mass | A dry air mass that forms over land. |
| convection | The transfer of heat by the movement of fluid. |
| Coriolis effect | The way Earth's rotation makes winds in the Northern Hemisphere curve tothe right and winds in the Southern Hemispher curve to the left. |
| cumulus | Clouds that form less than 2 km above the ground and look like fluffy, rounded piles of cotton. Usually means fair weather. |
| cyclone | A swirling center of low air pressure. |
| dew point | The temperature at which condensation begins. |
| El Nino | Occurs every 2-7 years; winds shift and push warm surface water toward the coast of S. America;can cause dramatic climate changes |
| evaporation | The process by which water molecules in liquid water escape into the air as water vapor. |
| front | The area where air masses meet and do not mix. |
| global winds | Winds that blow steadily from specific directions over long distances. |
| greenhouse effect | The process by which heat is trapped in the atmosphere by water vapor, carbon dioxide, methane, and other gases that form a "blanket" around the Earth. |
| humidity | A measure of the amount of water vapor in the air. |
| hurricane | A large tropical storm with high winds. |
| isobars | Lines on a map joining places that have the same air pressure. |
| isotherms | Lines on a map joining places that have the same temperature. |
| jet streams | Bands of high-speed winds about 10 km above Earth's surface. |
| land breeze | The flow of air from land to a body of water. |
| local winds | Winds that blow over short distances. |
| maritime air mass | A humid air mass that forms over oceans. |
| monsoons | Sea and land breezes over a large region that change direction with the seasons. |
| occluded | Cut off, as the warm air mass at an occluded front is cut off from the ground by cooler air beneath it. |
| polar air mass | A cold air mass that has high pressure. |
| precipitation | Any form of water that falls from clouds and reaches Earth's surface |
| psychrometer | An instrument used to measure relative humidity, consisting of a wet-bulb and dry-bulb thermometer. |
| radiation | The direct transfer of energy by electromagnetic waves. |
| rain gauge | An instrument used to measure the amount of preciptation. |
| relative humidity | The percentage of water vapor in the air compare to the maximum amount the air could hold at that temperature. |
| sea breeze | The flow of air from an ocean or lake to the land. |
| storm | A violent disturbance in the atmosphere. |
| storm surge | A dome of water that sweeps across the coast where a hurricane lands. |
| stratus | Smooth gray clouds that cover the whole sky;usually with light rain or drizzle. |
| temperature | The average amount of energy of motion in the molecules of a substance. |
| thermometer | An instrument used to measure temperature. |
| tornado | A rapidly whirling, funnel-shaped cloud that reaches down from a storm cloud to touch Earth's surface. |
| tropical air mass | A warm air mass that forms in the tropics and has low air pressure. |
| water vapor | Water in the form of a gas. |
| weather | The condition of Earth's atmospher at a particular time and place. |
| wind | The horizontal movement of air from an area of high pressure to an area of lower pressure. |
| wind-chill factor | Increased cooling caused by the wind evaportaing water vapor. |
| rain | Precipitation equal to one million cloud droplets. |
| sleet | When raindrops pass through an extremely cold layer of air, they sometimes freze into small ice pellets. |
| snow | Precipitation that changes directly into a solid. |
| hail | Preciptation that forms in cumulonimbus clouds when water droplets hit ice pellets in the clouds and freeze. An updraft makes them larger. |
