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Sky and SpaceSky and Space
Lecture Outline #3Lecture Outline #3
Moisture in the AtmosphereMoisture in the Atmosphere
Water in the AtmosphereWater in the Atmosphere
HumidityHumidity CloudsClouds FogFog PrecipitationPrecipitation
Three Phases of WaterThree Phases of Water
HumidityHumidity
How much water vapor is in the How much water vapor is in the atmosphere?atmosphere?
3 Ways to Express Humidity3 Ways to Express Humidity
Absolute HumidityAbsolute Humidity Specific HumiditySpecific Humidity Relative HumidityRelative Humidity
Relative HumidityRelative Humidity
WARM AIR HOLDS MORE WATER WARM AIR HOLDS MORE WATER VAPOR THAN COLD AIRVAPOR THAN COLD AIR
Changes in HumidityChanges in Humidity
Relative Humidity after CoolingRelative Humidity after Cooling
Relative Humidity and TemperatureRelative Humidity and Temperature
Warm Air is Capable of Holding More Water Vapor than Cold Warm Air is Capable of Holding More Water Vapor than Cold AirAir
Dew PointDew Point
When air is cooled, it can reach 100% When air is cooled, it can reach 100% Relative Humidity (saturation)Relative Humidity (saturation)
Dew PointDew Point
When air is cooled to a certain temperature, When air is cooled to a certain temperature, it can reach 100% Relative Humidity it can reach 100% Relative Humidity (saturation)(saturation)
There is more Condensation There is more Condensation than evaporation after dew point than evaporation after dew point is reached.is reached.
Dew PointDew Point
When air is cooled to a certain temperature, When air is cooled to a certain temperature, it can reach 100% Relative Humidity it can reach 100% Relative Humidity (saturation)(saturation)
Condensation Occurs at this temperatureCondensation Occurs at this temperature
This is the Dew Point This is the Dew Point TemperatureTemperature
Basics of Cloud FormationBasics of Cloud Formation
Warm air contains more water vapor than Warm air contains more water vapor than cold aircold air
Hot fluids rise (convection)Hot fluids rise (convection) In the troposphere, temperature decreases In the troposphere, temperature decreases
with altitudewith altitude When water vapor in the air cools, it When water vapor in the air cools, it
condensescondenses An air parcel can cool at a different rate An air parcel can cool at a different rate
than surrounding airthan surrounding air
Cloud FormationCloud Formation
Adiabatic CoolingAdiabatic Cooling
Rising Parcel cools quicker than Rising Parcel cools quicker than surrounding airsurrounding air
Parcel remains warmer than the Parcel remains warmer than the surrounding airsurrounding air
Conditional InstabilityConditional Instability Rising parcel cools Rising parcel cools
quicker than quicker than surrounding airsurrounding air
Reaches dew pointReaches dew point
Then cools slower Then cools slower than surrounding than surrounding airair
What forces air to rise?What forces air to rise?