How is Weather Predicted?

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Lesson 4-3

• How is Weather Predicted?

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• Meteorology study of weather
• A. Instruments used to study weather
• 1. Thermometer measures air temperature
• 2. Barometer measures air pressure
  (barometric pressure)
• a. rising barometer -gt increase in air
  pressure -gt arrival of colder air
• b. rising barometer -gt less humidity -gt
  lower chance of rain
• c. falling barometer -gt more humidity -gt
  higher chance of rain

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• 3. Anemometer measures wind speed
• a. windsocks wind vanes measure wind
  direction
• 4. Hygrometer measures humidity
• 5. Observe the sky and clouds
• a. Cirrus small Cumulus clouds -gt
  fair weather ahead
• b. Large gray Cumulus clouds -gt rain is
  probably on the way

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• Air Masses large body of air that has the same
  temperature humidity throughout
• A. Take on characteristics of region over
  which they form
• B. When weather changes in an area, the air
  mass over the area also changes
• C. Change in air mass -gt change in air
  pressure -gt winds
• D. Most move West to East in the U.S.

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• Front border where two air masses meet (high
  pressure meets low pressure)
• A. Most weather changes occur along fronts
• B. High pressure usually is Cold, dense and
  dry air.
• C. Low pressure is usually Warm, light and
  humid air.
• D. A Warm front usually brings rain or snow
  that can last for hours.
• E. A Cold front usually brings heavy rain
  for a short time, then clear cool weather.

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Cold Front
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Cold Front
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Warm Front
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Warm Front
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• Weather Maps give information about what the
  weather is like in an area
• A. Show
• 1. sun/clouds/rain/snow
• 2. warm/cold fronts
• 3. temperature