front

Where air masses meet and do not mix.

warm front

the leading edge of a moving mass of warm air.

stationary front

when a cold and a warm air mass meet, but neither moves.

stratus

lower level; layered-looking clouds.

condensation

the process by which a gas becomes a liquid. Water vapor turns into liquid water by condensation.

evaporation

the process by which a liquid becomes a gas.

run-off

the flow of water, from rain, snowmelt, or other sources, over the land.

saturated

thoroughly full.

watershed

an area of land that is drained by a stream or river and its branches.

temperature

a measurement of the amount of heat a substance contains.

stratus

a cloud belonging to a class characterized by horizontal layering with a uniform base. More specifically, the term stratus is used to describe flat, featureless clouds of low altitude varying in color from dark gray to nearly white.cloud

prevailing winds

the trends in speed and direction of wind over a particular point on the earth's surface.windearth

Westerlies

Any semipermanent belt of westerly winds, especially those that prevail at latitudes lying between the tropical and polar regions of the earth

Easterlies

A storm or wind coming from the east

pattern

a repeating arrangement of shapes, colors, numbers, or other things.

air mass

a body of air that has the same temperature and/or humidity throughout.

air pressure

the pressure exerted by air per-unit surface area in the earths atmosphere. Also called barometric pressure.

almanac

a publication that contains astronomical and meteorological data and forecasts.

aneroid barometer

a barometer that does not require the use of a liquid.

atmosphere

the layer of air that surrounds the earth.

barometer

a device used to measure air pressure.

beaufort scale

a scale that relates the wind speed to its effects booth on land and at sea, classified from force 0 to force 12.

cirrus

high level clouds made mostly of ice crystals.

climate

the average weather over a long period of time.

cumulonimbus

clouds that bring summer storms, usually with thunder, lighting, and strong winds.

cumulus

mid-level, puffy clouds.

fog

clouds that form at ground level.

forecast

a prediction of the weather conditions for a given area and a given time period.

hurricane

a large rotating windstorm with a calm central eye and winds greater than 118 kph.

isobar

lines drawn on a weather map that connect areas of the same barometric pressure at a given time.

meteorologist

a person who studies meteorology.

meteorology

the study of the earths atmosphere and what happens in it.

occluded front

where a cold front catches up to and overtakes a warm front.

precipitation

any liquid or solid form of water that falls from the atmosphere. For example, rain, snow, hail, or sleet.

rain gauge

a device used to measure the amount of precipitation in a given area.

station model

a weather symbol that represents the state of the weather at a particular place.

stratus

lower level; layered-looking clouds.

tornado

a narrow, violently rotating column of air characterized by winds greater than 81 kph and a funnel cloud that reaches the ground.

vacuum

an area of no air pressure.

weather

the state of the atmosphere at a given time and place with respect to wind, temperature, cloudiness, moisture, pressure, and other factors.

weather forecasting

predicting what future weather will be like.

weather front

the boundary where difficult air masses collide.

weather station

a place where weather data are recorded.