Horizontal movement of air between cooler and warmer regions. - horizontal movement of air Convection over areas where is

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1 Winds and Water Chapter 9 continued... Uneven Heating The various materials of the earth absorb and emit energy at different rates Convection Heated air expands; density reduced; air rises Upward movement of air over a heated surface Convection Cooled air contracts; density increased; air sinks Downward movement of air over a cooled surface Horizontal movement of air between cooler and warmer regions - horizontal movement of air Convection over areas where is Clear sky indicates air is moving downward Average Wind Speed - 10 mi/hr (know) Differences in Atmospheric Pressure Convection Cell Sea Breezes and Land Breezes Uneven heating of land and water High specific heat of water Heat spread out in water Sea Breeze (KNOW) Land Breeze (KNOW) Mountain Breezes

2 A of with sharp that can sublimate or melt away any existing snow cover in a single day Santa Ana Winds Warm dry winds blowing westward High pressure area over Great Basin Great Basin High Santa Ana Winds Low pressure zone off the coast destabilizes Great Basin High Air moves down across Southern California Santa Ana Winds Compressional heating of air 5 F / 1000 ft Hot, dry winds Global Wind Patterns Unequal Heating of the Earth Equator receives more direct incoming solar radiation higher average temperatures temperatures decrease toward the poles Coriolis Effect on Wind Patterns Winds are bent by the spinning of the Earth: to the right north of the equator to the left in the south. Low Pressure Region between and latitude Warm air rises

3 Heavy precipitation --unusually calm or very light winds 30 North and 30 South Great Desert Biome Blow from the horse latitudes toward the low pressure of the ITCZ (know this definition) Northeast Trade Winds blow from the northeast Southeast Trade Winds blow from the southeast between 30 and 60 latitude north and south blows from horse latitudes toward poles responsible for many of the across the and Canada. Polar Easterlies formed as cold air at the poles sinks and begin to move towards the equator. meet warmer air from the westerlies and create a polar front located at 60 degrees north and south area of low pressure that often results in storms. Winds Poleward

4 Above the High Pressure Belt are controlled by the jet stream that blow than miles per hour marks the boundary between cold polar air to its north and warmer air to its south (northern hemisphere). blows west to east Upper Above 20,000 feet 6-9 miles Jet Stream Up to 300 mph Circle the globe Few hundred miles wide Less than 3 miles thick Jet Stream Surface temperature contrasts the greater the contrast the faster the flow in Jet Stream Affects Weather Warm air masses move northward ahead of trough Cold air masses move southward behind trough The States of Water Water vapor Water existing as a gas Moist air contains a lot of water vapor Concentration of Water Vapor Over of on Earth is

5 If all the water vapor in the atmosphere condensed: I inch of water would cover the Earth Water Vapor Services Contributes to greenhouse effect warmer planet Weathering and erosion Maintains life water cycle of the average of a substance The more kinetic energy a molecule has, the faster it is moving Water molecule escapes and becomes a gas High kinetic energy Headed in right direction Overcomes attractive forces More molecules are leaving than returning (KNOW) Water molecule captured by other water molecules More water molecules are returning than leaving (KNOW) Equilibrium evaporation condensation Temperature and Saturation Molecules with higher kinetic energies are less likely to be pulled together Warm air holds more water vapor The of in the High humidity

6 more condensation Low humidity more evaporation Absolute Humidity A measurement of the amount of water vapor in the air at a particular time A between (1) the amount of water vapor in the air and actual humidity (2) the amount of water vapor needed to saturate the air at that temperature humidity Relative Humidity Playing with relative humidity the air the of air to hold Playing with relative humidity Dry winter air Just warming the air reduces relative humidity 50% - 3% Evaporation increases cooling process Warm up using humidifier Playing with relative humidity Wind Chill Factor Cooling power of the wind Evaporation increased reduces chances of condensation no latent heat of vaporization relative humidity declines Playing with relative humidity It s not the heat, it s the humidity Humidity slows the rate of evaporation Fans will increase evaporation At relative humidity, a is going to

7 Measuring Relative Humidity Measure evaporation of wet bulb evaporation lowers temperature Measure temperature difference See Appendix C Measuring Relative Humidity Hair Hygrometer Hair becomes less curly in humid weather Hair absorbs moisture from the air and becomes longer Length of hair = RH Condensation Condensation For condensation to occur, the air must be saturated water vapor added through evaporation cooling increase in RH distillation temperature at which sublimation Clear, Calm, and Cool Nights Loss of infrared radiation Clouds serve as a blanket Trees do the same Grass covered with frost more surface area greater loss of infrared radiation Clear, Calm, and Cool Nights Dew and frost form first in low-lying areas cold air sinks

8 Citrus orchards placed on slopes Clear, Calm, and Cool Nights Wind mixes upper warm air with lower cool air fans in orchards