Temperature Temperature average KE of molecules or average speed of molecules Warm air is less dense cool air is more dense Temperature Scales Kelvin scale Based on absolute zero temperature at which all motion stops 273o C 459o F 0o K Centigrade Celsius Water freezes at 0oC and boils at 100oC Fahrenheit Water freezes at 32oF and boils at 212oF Converting oC to oF Double the C temperature and then add 30 close nuff most of the time o C 1 8 32 oF Influences on Temperature 1 Latitude 2 Altitude 3 Atmospheric circulation weather clouds wind 4 Contrasts between land and water 5 Warm and cold ocean currents 6 Local impacts on temperature LATITUDE Remember how the seasons work Isotherms Lines of equal temperature Latitude 23 Jun 2007 ALTITUDE Remember that temperature decreases with height in the troposphere C B Temp A Temp B Temp C Temp B Why A Daily temperatures weather When solar energy in longwave energy out temperature rises Maximum occurs in late afternoon clouds haze humidity and ground cover control timing and maximum value Minimum occurs just before sunrise Solar Heating Radiational Cooling Seasons pp 43 50 Know and understand figure2 11 and 2 12 on p 44 September 22 23 December 21 22 March 21 22 June 21 22 Summer solstice N H Autumnal fall and vernal spring equinoxes 12 hour day everywhere Equinox at the North Pole Winter Solstice N H Lag in seasonal temperatures Most incoming radiation occurs on Jun 21st but hottest air temperatures happen in July Aug Similar opposite case with winter solstice Time lag caused by earth s surface specific heat High latitudes lose more energy to space than they receive from sun each year opposite in the lower latitudes Energy transport must occur to balance Daily Temperature Variations Daytime warming begins as conduction in layer nearest warm ground On a calm day convection can t influence the lowest portion of the air can get temperature profile like this Effects of winds on lower atmospheric temperatures Check out the wind Chill chart on Page 83 Wind causes forced convection much more efficient vertical transfer of heat Therefore surface is cooler than expected as upper level cool air mixes with surface warm air Day Night Radiation Differences During day the absorption gain from the sun s short wave radiation is greater than the earth s long wave radiation loss so temperature rises During night the earth s long wave radiation loss is greater so temperature falls Radiation Inversion Air temperature usually decreases with height lapse rate At night ground cools and air near ground can become much cooler than air above radiation inversion forms Temperature increases with height usually not much higher than 300 feet above the ground Extremely stable conditions fog often forms as air reaches Dew Point temperature Long nights calm winds dry and cloud free atmosphere are most favorable conditions for inversion formation Formation of Radiation Inversion How does the nighttime temperature profile change on a windy night Impact of clouds on daily temperature During the day solar radiation is blocked by clouds Therefore temperature is cooler at the surface than On a clear day During the nighttime clouds Cause outgoing longwave radiation To be trapped Therefore Temperature is warmer than on a Clear night Land vs coast Water holds heat longer therefore it heats up slower and cools down slower than The land If you live near a large body of water it will act like insulation During the day water will heat slowly And take heat away from the coastal City Temp Ft Walton Beach Temp Crestview During the night water will release heat slowly and keep the coastal city warmer Temp Ft Walton Beach Temp Crestview Forecast Cooler or Warmer 1 Daytime Coastal city vs Inland city 2 Nighttime Coastal city vs Inland city 3 Daytime city with clear skies vs city with cloudy skies 4 Nighttime city with clear skies vs city with cloudy skies 5 Daytime city at 6 000ft vs city at sea level 6 Nighttime city at 300ft vs city at sea level
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