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Weather Fronts. Air Mass. A large body of air with properties similar to the part of Earth’s surface that it covers. Air Mass.
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Air Mass • A large body of air with properties similar to the part of Earth’s surface that it covers.
Air Mass • Air masses with moisture form over water and dry air masses form over land. Air masses that form at the poles are cold and the ones that form in the tropics (near the equator) are warm.
Frontal Boundaries • Where air masses meet a boundary, known as a front, is created. • 4 kinds of fronts: • Cold front • Warm front • Occluded front • Stationary front
Back to activity Cold Front • Shown on a weather map by a blue line with triangles pointing in the direction that the cool air is moving.
Back to activity Cold Front • A cold air mass forces a warm air mass to rise. • As the warm air rises, clouds and precipitation are formed. • If the air is pushed upward quickly, cumulus and cumulonimbus clouds can form and violent storms can result. • As the front advances, temperatures usually drop.
Back to activity Warm Front • Shown on a weather map by a red line with half circles pointing in the direction that the warm air is moving.
Back to activity Warm Front • A warm air mass catches up to and slides over acooler air mass. • Many miles ahead of the front high cirrus clouds form. • As the front approaches, steady rain or snow can occur over a wide area as a result of the nimbostratus and cumulonimbus clouds that form. • After the front passes, wind direction changes and temperature rises.
Comparing Warmand Cold Fronts • Cold fronts move faster than warm fronts. • The weather activity in a cold front is often violent and happens directly at the front. • Cold fronts have sudden gusty winds high in the air creating turbulence. • The weather activity in a warm front generally happens before the front passes.
Back to activity Occluded Fronts • Shown on a weather map by a purple line with alternating triangles and semicircles pointing in the direction that the front is moving.
Back to activity Occluded Fronts • When a slow moving warm air mass is trapped between two fast moving cold air masses and forced to rise. • Stratus, nimbostratus & cumulonimbus clouds form and short steady precipitation often result.
Back to activity Stationary Fronts • Shown on a weather map with alternating red semicircles pointing away from the warm air and blue triangles pointing away from the cold air.
Back to activity Stationary Fronts • A warm air mass and a cold air mass meet, but neither move forward. • This can result in days of steady precipitation in the same area as a result of nimbostratus and cumulonimbus clouds.
Locate the 4 types of fronts on this weather map. Hint 1 Hint 2 Hint 3 Hint 4
Be a Weather Forecaster You are planning to travel to Alabama in 2 days. The high temperature there for today is 68º F. Use the map to help you predict whether the temperature in Alabama will increase, decrease, or stay the same. Explain why you think so.
Be a Weather Forecaster There is a cold front approaching. The temperatures will probably be cooler behind the front.
Be a Weather Forecaster • Of course, meteorologists (weather forecasters) use much more data than fronts and air masses to help them forecast the weather more accurately. But any forecast is just a prediction of what might happen. Even with the best data, weather forecasts can be wrong.
