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AOSC 200 Lesson 3

AOSC 200 Lesson 3. Fig. 3-1, p. 54. Diurnal temperature cycle. Fig. 3-3, p. 56. Air temperature data. Daily mean temperature is determined by two methods, (a) average of 24 hourly measurements (b) the average of the maximum and minimum temperatures for the day.

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AOSC 200 Lesson 3

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  1. AOSC 200Lesson 3

  2. Fig. 3-1, p. 54

  3. Diurnal temperature cycle Fig. 3-3, p. 56

  4. Air temperature data • Daily mean temperature is determined by two methods, (a) average of 24 hourly measurements (b) the average of the maximum and minimum temperatures for the day. • Daily temperature range is the difference between the max and min temperatures. • Monthly mean temperature is obtained from the average of the daily mean for the month • Annual mean temperature is the average of the monthly means • Annual temperature range is the difference between the coldest monthly mean and the warmest monthly mean

  5. CONTROLS OF TEMPERATURE • LATITUDE • SURFACE TYPE • ELEVATION AND ASPECT • DIFFERENTIAL HEATING OF LAND AND WATER. • OCEAN CURRENTS. • CLOUD COVER AND ALBEDO

  6. Fig. 3-4, p. 57

  7. Fig. 3-5, p. 57

  8. Fig. 3-6, p. 58

  9. Fig. 3-7, p. 59

  10. The effect of Aspect Fig. 3.8

  11. Fig. 3-9, p. 60

  12. Differential Heating of Land and Water • AS WATER IS HEATED CONVECTION DISTRIBUTES THE HEAT THROUGH A LARGE MASS. • IN CONTRAST, HEAT DOES NOT PENETRATE DEEPLY INTO SOIL OR ROCK - HEAT CAN ONLY BE TRANSFERRED BY CONDUCTION. • NET RESULT IS THAT A RELATIVELY THICK LAYER OF WATER IS HEATED TO MODERATE TEMPERATURES, WHILE ONLY A THIN LAYER OF LAND IS HEATED TO MUCH HIGHER TEMPERATURES. • SPECIFIC HEAT (AMOUNT OF HEAT NEEDED TO RAISE THE TEMPERATURE OF ONE GRAM OF A SUBSTANCE 1 DEGREE CELSIUS) IS ALMOST THREE TIMES GREATER FOR WATER THAN FOR LAND

  13. Fig. 3-10, p. 60

  14. Fig. 3-11, p. 61

  15. Effect of clouds on the daytime energy budget at the surface

  16. Fig. 3-13, p. 62

  17. Fig. 3-16, p. 67

  18. DAILY MARCH OF TEMPERATURE • AT THE BEGINNING OF THE DAY, WITH NO SOLAR RADIATION, THE TEMPERATURE IS CONTROLLED BY NET THERMAL RADIATION LEAVING THE SURFACE ---- THE GROUND COOLS. • AS SUN COMES UP , SOLAR RADIATION IS ABSORBED AND THE TEMPERATURE OF THE GROUND INCREASES - INCREASING THE NET THERMAL RADIATION LEAVING THE GROUND. • HOWEVER, IN GENERAL THE INCOMING SOLAR ENERGY IS MORE THAN THE NET OUTGOING THERMAL ENERGY, SO THE GROUND HEATS UP. • THE GROUND WILL CONTINUE TO HEAT UP UNTIL THE AMOUNT OF INCOMING SOLAR ENERGY EQUALS THE AMOUNT OF OUTGOING THERMAL ENERGY. • THIS OCCURS TYPICALLY AT ABOUT THREE/FOUR IN THE AFTERNOON. • SIMILAR ARGUMENTS EXPLAIN THE LAG SEEN IN THE WINTER AND SUMMER.

  19. CONTROLS OF DIURNAL TEMPERATURE RANGE • LATITUDE - DETERMINES THE INTENSITY OF THE SUN, AND THE LENGTH OF THE DAY • SURFACE TYPE - LAND AND WATER CONTRAST, BARE SOIL VERSUS VEGETATION • ELEVATION AND ASPECT • RELATIONSHIP TO LARGE BODIES OF WATER - LARGE BODIES OF WATER ACT LIKE A THERMOSTAT - TEMPERATURE RANGE IS SMALLER • OCEAN CURRENTS. • CLOUD COVER - REDUCES THE DIURNAL TEMPERATURE RANGE.

  20. Fig. 3-14, p. 63

  21. Interannual Temperature Variations • AVERAGE OR NORMAL TEMPERATURES • ANOMALIES • VOLCANOES • EL NINO / LA NINA

  22. Volcanoes Fig. 3-15a, p. 66

  23. Picture taken by astronauts on the Space Shuttle 3 weeks after the eruption of Mt. Pinatubo Fig. 3.15b

  24. Temperature in Spokane and Boise after the eruption of Mount St. Helens Box 3-1, p. 64

  25. http://www.youtube.com/watch?v=dQeCEqkE9eE http://www.youtube.com/watch?v=dQeCEqkE9eE

  26. Fig. 3-17, p. 72

  27. Fig. 2.7

  28. Adiabatic Cooling and Warming • A RISING PARCEL OF AIR ALWAYS EXPANDS • AS THE PARCEL EXPANDS IT WILL COOL • ADIABATIC PROCESS - NO HEAT EBERGY IS GAINED OR LOST BY THE PARCEL • THE RATE OF COOLING WITH ALTITUDE DUE TO THIS PROCESS IS CALLED THE DRY ADIABATIC LAPSE RATE • USUALLY THE AIR CONTAINS SOME WATER VAPOR • AS THE PARCEL RISES AN ALTITUDE WILL BE REACHED WHEN THE WATER VAPOR CONDENSES • BUT THIS RELEASES LATENT HEAT OF CONDENSATION TO THE AIR PARCEL • THEREFORE THE TEMPERAURE OF THE PARCEL WILL NOT DROP OFF AS MUCH AS FOR A DRY PARCEL OF AIR • WET ADIABATIC LAPSE RATE

  29. Fig. 3-18, p. 73

  30. Lapse Rates and Stability • Lapse rate is the rate at which the real atmosphere falls off with altitude – the environmental lapse rate • An average value is 6.5 ºC per kilometer • This should be compared with the adiabatic lapse rate of 10 ºC. • If the environmental lapse rate is less than 10 ºC, then the atmosphere is absolutely stable • If greater than 10 ºC, it is absolutely unstable

  31. Fig. 3.12 • Lifecycle of a nocturnal (radiative) temperature inversion • Mid-afternoon • Evening • Sunrise • Mid-morning Fig. 3-19, p. 75

  32. Temperature Inversions • When the temperature profile increases with altitude, this is known as a temperature inversion • Two main types – subsidence inversion and radiation inversion (nocturnal inversion) • Very important during pollution events – trap pollutants close to the surface.

  33. Temperature Inversions

  34. Effect of a temperature inversion Fig. 3-20, p. 77

  35. Wind Chill Factor • The wind chill factor describes the increased loss of heat by the movement of air • It cannot be measured, so it is calculated • Wind chill equivalent temperature

  36. Table 3-1, p. 78

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