Humidity
- 1. Humidity
- 2. Visualizing Physical Geography Copyright © 2008 John Wiley and Sons Publishers Inc. Humidity Humidity : the amount of water vapor in the air The maximum quantity of moisture that can be held in the air depends on air temperature
- 3. Visualizing Physical Geography Copyright © 2008 John Wiley and Sons Publishers Inc. Humidity Relative Humidity : compares the amount of water vapor present in the air to the maximum amount that the air can hold at that temperature Expressed as a percentage: At 100% relative humidity, air is saturated.
- 4. Visualizing Physical Geography Copyright © 2008 John Wiley and Sons Publishers Inc. Humidity Relative Humidity changes when: Atmosphere gains or loses water vapor Evaporation Temperature changes Lower temperature relative humidity rises Raise temperature relative humidity decreases
- 5. Visualizing Physical Geography Copyright © 2008 John Wiley and Sons Publishers Inc. Humidity Specific Humidity : actual quantity of water held by a parcel of air Grams of water vapor per kilogram of air (g/kg) Highest in equatorial zones Lowest near poles
- 6. Visualizing Physical Geography Copyright © 2008 John Wiley and Sons Publishers Inc. Dew-point temperature : temperature at which air with a given humidity will reach saturation when cooled without changing its pressure Humidity
- 7. Visualizing Physical Geography Copyright © 2008 John Wiley and Sons Publishers Inc. The Adiabatic Process Adiabatic Principle : the physical principle that a gas cools as it expands and warms as it is compressed Change in temperature: caused only by a change in pressure not caused by heat flowing in or out of the gas
- 8. Visualizing Physical Geography Copyright © 2008 John Wiley and Sons Publishers Inc. The Adiabatic Process As a parcel of air rises pressure on the parcel decreases air expands and cools As a parcel of air descends pressure on the parcel increases air is compressed and warms Atmospheric pressure decreases with altitude so...