Pressure Systems and Fronts

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Pressure Systems and Fronts
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Pressure Systems

• Air Pressure is caused by the weight of air
  molecules above
• Air pressure is related to density, air
  temperature, and distance from the Earths
  Surface

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High and Low Pressure Systems

• High Pressure causes air to flow down and fan out
• This tends to cause clear, cool weather because
  sinking air prevents cloud formation

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• Low Pressure causes air to flow up
• Rising air cools and condensation occurs
• Low pressure causes warm, rainy, cloudy weather

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Fronts

• Air masses interact with each other, and fronts
  are the boundaries between them

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• Cold Fronts
• Rapid uplifts form cumulus clouds
• May produce thunderstorms, tornadoes or snow
  squalls
• Causes abrupt temperature drop

• Warm Fronts
• Moves slower than a cold front
• Less severe weather
• Produces cirrus, then stratus clouds
• Steady precipitation that can last for days

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• Stationary Front
• Neither mass is moving
• Brings stratus clouds and rain
• Gloomy, dreary sky