WEATHER

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WEATHER

• TOPIC 7

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ATMOSPHERIC MOISTURE

• 3 processes for water to enter atmosphere
• Evaporation liquid ? gas
• Transpiration plants release water vapor
• Sublimation solid ? gas
• Main source of water vapor oceans
• Evapotranspiration Evaporation
• transpiration

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ATMOSPHERIC MOISTURE

• Factors affecting the Rate of Evaporation
• Amount of energy available
• Surface area of water
• Amount of water vapor already in the air above
  the water degree of saturation
• see Fig 7-9, p. 117
• Wind speed

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ATMOSPHERIC MOISTURE

• Dynamic Equilibrium
• Rate of Rate of
• Evaporation Condensation

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ATMOSPHERIC MOISTURE

• Humidity the amount of water vapor in the
  atmosphere
• also Moisture Capacity
• Absolute Humidity actual amount of water vapor
  in the air
• unit g/m3

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ATMOSPHERIC MOISTURE

• Relative Humidity the amount of water vapor in
  the air compared to the amount the air could hold
  at that specific temperature.
• RATIO
• expressed as a percentage

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ATMOSPHERIC MOISTURE

• Psychrometer instrument used to measure
  relative humidity.

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ATMOSPHERIC MOISTURE

• Dew Point temperature at which the relative
  humidity is 100.

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ATMOSPHERIC MOISTURE

• Determining Dew Point
• (see ESRB p. 119)
• Locate dry-bulb reading (row).
• Subtract wet-bulb reading from dry-bulb reading
  to calculate the difference.
• Locate difference between wet-bulb dry-bulb
  readings (column).
• Find point where dry-bulb row intersects with
  difference column.

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