Air Masses and Fronts

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Air Masses and Fronts
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Air Mass

• A large body of air
• At least 1,000 miles across
• Uniform temperature and humidity
• Flows as one unit

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Air Mass

• Four main types
• Cold (polar)
• Warm (tropical)
• Water (maritime)
• Land (continental)
• Combinations
• Maritime tropical
• Maritime polar
• continental tropical
• Continental polar

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Fronts

• When two air masses meet

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Fronts

• Warm frontWhen a warm air mass overrides a cold
  area, it rises slowly, creating nimbostratus,
  altostratus or cirrostratus clouds. This can
  produce light precipitation.

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Fronts

• Cold frontWhen a cold air mass overrides a warm
  area, it pushes the warm air up forcefully,
  creating cumulus and cumulonimbus clouds. Cold
  fronts often produce thunderstorms and very bad
  weather.

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Fronts

• Stationary frontWhen a cold air mass and warm
  air mass flow side-by-side, and neither mass
  invades the other, weather can by unpredictable.
  It most often resembles a warm front, with light
  rain if any precipitation occurs.

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Fronts

• Occluded frontWhen two cold air masses trap a
  warm air mass, they push the warm air up. The
  boundary that exists is between two similar air
  masses cold and cooler air. Clouds and
  precipitation are likely.

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Mid-latitude Cyclones

• Severe storms that develop between tropical and
  polar air masses in mid-latitude regions around
  low-pressure centers.