All terms in this list:

air mass: large body of air that has the same characteristics of temperature and moisture content as the part of earth's surface over which is formed.

blizzard: winter storm that last at least 3 hours with temperatures of -12 degrees celsius or below, poor visibility, and winds of at least 51 km/h.

dew point: temperature at which air is saturated and condensation forms.

fog: a stratus cloud that forms when air is cooled to its dew point near the ground.

front: boundary between two air masses with different temperatures, density, or moisture; can be cold, warm, occlude, and stationary.

humidity: amount of water vapor held in the air.

hurricane: large, severe storm that forms over tropical oceans, has winds of at least 120 km/h, and loses power when it reaches land.

isobars: lines drawn on a weather map that connect points having equal atmospheric pressure; also indicate the location of high-pressure and low-pressure areas and can show wind speed.

isotherm: line drawn on a weather map that connects points having equal temperature.

meteorologist: studies weather and uses information from Doppler radar, weather satellites, computers and other instruments to make weather maps and provide weather forecasts.

precipitation: water falling from clouds-including rain, snow, hail, and sleet- whose form is determined by air temperature.

relative humidity: a measure of the amount of weather vapor present in the air compared to the amount needed for saturation at a given temperature; can range from 0 to 100 percent.

station model: indicates weather conditions at a specific location, using a combination of symbols on a map.

tornado: violent, whirling wind that crosses land in a narrow path and can result from wind shears inside a thunderhead.

weather: state of the atmosphere at a specific time and place, determined by factors including air pressure, amount of moisture in the air, temperature, and air.