GEO 155 1st Edition Lecture 8 Outline of Last Lecture I General Circulation and Moisture in the Atmosphere Outline of Current Lecture I Moisture in the Atmosphere a Phase Changes b Relationship between Air Temperature and Maximum Water Vapor i Saturation ii Dew Point c Humidity d Ways to Reach Saturation i Mixing ii Cooling 1 Diabatic Cooling 2 Adiabatic Cooling Current Lecture Moisture in the Atmosphere Phase Changes 1 Latent Cooling used for a Ice to melt to liquid water b Water to evaporate to water vapor 2 Heat released during a Water vapor condensing to water b Liquid water freezing to ice Air Temperature and Amount of Water Vapor Warm air can hold more vapor than cold air 1 Saturation Curve tells how much vapor air can hold at a given temperature 2 Dew Point the temperature that air is saturated at These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Humidity 1 Actual Humidity how much vapor is in the air 2 Saturation Humidity how much vapor the air could hold o Depends on the temperature 3 Relative Humidity how full the air is o Calculated by dividing Actual over Relative Humidity and multiplied by 100 o Need 100 for condensation the closer the percentage is to 100 the more likely condensation will occur Air needs to be saturated for condensation to occur Humidity is measured in g m 3 How to Reach Saturation 1 Mixing Cooling mix together two parcels of air one at a cooler temperature and one at a warmer temperature when mixed they are too saturated to reach the curve so they condense a Jet Contrails b Cold dry land has cold dry air above it the land surrounds a warm body of water that has warm moist air above it a breeze blows the cold dry air over the body of water causing them to mix leading to saturation and condensation 2 Cooling take unsaturated air and cool it until it reaches dew point and 100 relative humidity a Diabatic Cooling change in the amount of energy i Advection Fog warm surface with warm air above it wind blows moves air to a place where the surface underneath it is cold warm air loses energy to the cold ground underneath it air cools if it reaches dew point condensation ii Radiation Fog warm surface has warm air above it sun goes down so it stops emitting shortwaves surface emits longwave radiation ground cools warm air loses energy to the ground air cools if it reaches dew point condensation will occur b Adiabatic Cooling lift parcel of air into the atmosphere pressure decreases Forms clouds precipitation i Air sinks compressed by more pressure energized adiabatic warming Mechanism of Uplift How to get air to rise 1 Orographic Uplift cause by a topographic barrier mountains a Air expands and cools condensation and precipitation b Downwind of mountain as air sinks there is a rain shadow or dry area 2 Frontal Uplift pushed up by other air 3 Dynamic Uplift pulled up by Jet Stream 4 Convective Uplift hot air rising
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