Science Ch 4 vocab Flashcards
Evaporation
The process by which molecules at the surface of a liquid absorb enough energy to change to a gas.
Water Cycle
The continual movement of water among Earth’s atmosphere, oceans, and land surface through evaporation, condensation, and precipitation.
Condensation
The change of state from a gas to a liquid.
Humidity
The amount of water vapor in a given volume of air.
Relative humidity
The percentage of water vapor in the air compared to the maximum amount of water vapor that air can contain at a particular temperature.
Psychrometer
An instrument used to measure relative humidity.
Dew point
The temperature at which condensation begins.
Cirrus
Wispy, feathery clouds made of ice crystals that form at high levels.
Cumulus
Fluffy, white clouds, usually with flat bottoms, that look like rounded piles of cotton.
Stratus
Clouds that form in flat layers and often cover much of the sky.
Precipitation
Any form of water that falls from clouds and reaches Earth’s surface as rain, snow, sleet, or hail.
Rain gauge
An instrument used to measure precipitation.
Flood
An overflowing of water in a normally dry area.
Drought
A long period of low precipitation.
Air Mass
A huge body of air that has similar temperature, humidity, and air pressure at any given height.
Tropical
A warm air mass that forms in the tropics and has low air pressure.
Polar
A cold air mass that forms north of 50° north latitude or south of 50° south latitude and has high air pressure.
Maritime
A humid air mass that forms over oceans.
Continental
A dry air mass that forms over land.
Jet stream
Bands of high-speed winds about 10 kilometers above Earth’s surface.
Front
The boundary where unlike air masses meet but do not mix.
Occlude
Cut off, as in a front where a warm air mass is caught between two cooler air masses.
Cyclone
A swirling center of low air pressure.
Anticyclone
A high-pressure center of dry air
