| A | B |
|---|
| accumulation | the collection of water into lakes, rivers and oceans |
| air mass | large volume of air in which temperature and humidity are nearly the same in different locations at the same altitude |
| air pressure | The measure of the force with which air molecules push on a surface. |
| cirrus | means "curl of hair", appear feathery or wispy; form in very cold air at high altitudes, usually occur in fair weather, but can be a sign of an approaching storm |
| cold front | forms when a cold air mass pushes a warm air mass and forces the warm air to rise, forms tall clouds |
| condensation | the process in which water vapor (a gas) in the air turns to liquid water; this process forms clouds in the sky |
| continental air mass | (describes MOISTURE) forms over land, air becomes dry as it loses moisture to the dry land below it |
| Coriolis Effect | effect of Earth's rotation on the direction of winds and currents. |
| cumulus | means "heap" or "pile"; puffy, white clouds, often with darker bases, look like floating cotton, usually occur in daytime during fair weather; form as warm air rises, can produce brief showers |
| dew point | The temperature (which is dependent upon the specific humidity and pressure) to which the air must be cooled for water vapor to condense and form fog, clouds, or dew |
| evaporation | the process in which liquid water becomes water vapor; the water comes from the surfaces of oceans and lakes, from the surface of the land, and from melts in snow fields |
| forecast | a prediction about how something (such as the weather) will develop |
| front | boundary between air masses |
| high-pressure system | large and changes slowly, generally brings clear skies and gentle breezes |
| humidity | a measure of the amount of water vapor in the air |
| isobar | A line on a weather map that joins places that have the same air pressure |
| low-pressure system | produces stormy weather, the air circles in a counter-clockwise direction in the Northern Hemisphere and in a clockwise direction in the Southern Hemisphere |
| maritime air mass | (describes MOISTURE) forms over water, air becomes moise as it gains water vapor from the water below it |
| meteorologist | a scientist who studies the weather |
| meteorology | the earth science dealing with phenomena of the atmosphere (especially weather) |
| polar air mass | (describes TEMPERATURE) forms far from the equator, air becomes cool as it loses energy to the cool land or water |
| precipitation | the process in which water, in the form of rain, snow, sleet or hail, falls from the sky |
| radar stations | locate clouds and measure their heights, detect air motion and precipitation |
| saturation | the most concentrated solution possible at a given temperature |
| severe weather | extreme, dangerous weather, such as powerful winds and intense precipitation; examples include hurricanes, tornados, blizzards, hailstorms, and thunderstorms |
| severe weather warning | An alert issued when dangerous weather (tornado, flood, etc) has been sighted or indicated by radar or other alerts |
| severe weather watch | An emergency alert that is issued when the weather conditions are such that a dangerous weather event (tornado, flood, etc) is likely to develop |
| stationary front | occurs when two air masses push against each other without moving |
| stratus | means "spread out", form in flat layers; can cause the whole sky to look gray, form in large areas when air cools without rising, produce steady, light precipitation |
| temperature | the degree of hotness or coldness of a body or environment (corresponding to its molecular activity) |
| tropical air mass | (describes TEMPERATURE) forms near the equator, air becomes warm as it gains energy from the warm land or water |
| UV Index | international standard measurement of how strong the ultraviolet (UV) radiation from the sun is at a particular place on a particular day |
| visibility | The greatest horizontal distance an observer can see and identify a prominent object |
| warm front | forms when a warm air mass pushes a cold air mass, the warm air rises slowly over the cold air, forms flat clouds |
| weather balloons | make important measurements of the air at different altitudes as they carry instruments high into the stratosphere |
| weather buoys | record the weather far from cities, measure conditions in the ocean that affect the atmosphere |
| weather forecast | a calculation in advance of weather conditions by analyzing meteorological data |
| weather satellites | orbit Earth above the atmosphere, show cloud cover, warm and cool regions, and invisible water vapor |
| wind | air moving (sometimes with considerable force) from an area of high pressure to an area of low pressure |
