TemperatureTemperature ScalesSlide 3Slide 4Slide 5Slide 6Daily temperatures & weatherSlide 8Summer solstice (N.H.)Autumnal (fall) and vernal (spring) equinoxesEquinox at the North PoleWinter Solstice (N.H.)Lag in seasonal temperaturesSlide 14Daily Temperature VariationsEffects of winds on lower atmospheric temperaturesDay – Night Radiation DifferencesRadiation InversionFormation of Radiation InversionSlide 20Slide 21Slide 22Temperature•Temperature=average KE of molecules, or average speed of molecules: Warm air is less dense, cool air is more denseTemperature 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 timeoC*1.8 + 32=oFInfluences on Temperature1. Latitude2. Altitude3. Atmospheric circulation-weather-clouds,wind4. Contrasts between land and water5. Warm and cold ocean currents6. Local impacts on temperatureIsotherms: Lines of equal temperatureLATITUDE—Remember how the seasons workLatitude23 Jun. 2007ALTITUDERemember that temperature decreases with height in the troposphereABCTemp A > Temp BTemp C >Temp BWhy??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 sunriseSolar HeatingRadiationalCoolingSeasons (pp.43-50)June 21-22March 21-22September 22-23December 21-22Know and understand figure2-11 and 2-12 on p.44Summer solstice (N.H.)Autumnal (fall) and vernal (spring) equinoxes12 hour day everywhereEquinox at the North PoleWinter 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 balanceDaily 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•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 airCheck out the windChill chart on Page 83!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 formationFormation of Radiation InversionHow does the nighttime temperature profile change on a windy night?Impact of clouds on daily temperatureDuring the day solar radiation is blocked by cloudsTherefore temperature is cooler at the surface thanOn a clear day.During the nighttime, clouds Cause outgoing longwave radiationTo be trapped. ThereforeTemperature is warmer than on a Clear night.Land vs. coastWater holds heat longer therefore it heats up slower and cools down slower thanThe 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 coastalCity. Temp Ft. Walton Beach < Temp. CrestviewDuring the night, water will release heat slowly and keep the coastal city warmer. Temp Ft. Walton Beach > Temp. CrestviewForecast: 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 skies4. Nighttime: city with clear skies vs. city with cloudy skies5. Daytime: city at 6,000ft vs. city at sea level6. Nighttime: city at 300ft vs. city at sea
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