Geography 103

Lecture 3: Air Temperature (Quiz 1)

1.  Kinetic molecular theory
     Temperature is determined by the mean molecular speed of a substance.
     High air temperature means faster air molecular speed.
2. Four types of energy
    (1). Kinetic energy: determined by speed (wind speed in the atmosphere).
    (2). Potential energy: determined by elevation (or air pressure in the atmosphere).
    (3). Latent heat: determined by moisture amount.
    (4). Internal energy (sensible): determined by air temperature.
3. Absolute temperature
    (1). 0 ^oC = 0 ^oF = 0 temperature??? (^oC or ^oF is a relative scale)
    (2). Absolute temperature scale: Kelvin (K).
    (3). Absolute zero temperature: 0 K = -273 ^oC.
    (4). K = ^oC + 273 (notice that K is not preceded by degree symbol because it is an absolute scale)
4. Normal temperature: 30-year average air temperature (from 1971 to 2000).
5. Lapse rate
    Air temperature change per unit height increase.
    (1). Regular (Normal) lapse rate:
          Air temperature decreases with increasing height, in average, about 0.65 ^oC/100m
    (2). Inversion
          Air temperature increases with increasing height, varying according to location and time.
    (3). Isothermal
          Air temperature remains constant with increasing height.
6. Atmospheric structure
    (1). Troposphere (weathersphere)
          A. Contains about 80% of the mass of the atmosphere.
          B. Region of clouds, weather, and vertical motion (turbulence).
          C. Topped by an inversion called tropopause.
          D. Lapse rate (average rate): -0.65 ^oC/100 m (-3.6 ^oF/1000 feet).
          E. Tropopause
              (A).   Middle Latitude (average): 11 Km (-57 ^oC or -71 ^oF)
              (B).   Tropics: 16 Km or 10 miles ( -73 ^oC or -100 ^oF).
              (C).   Poles: 6 Km or 3.6 miles (-42 ^oC or -45 ^oF).
    (2). Stratosphere (ozonosphere)
           A. Cloudless.
           B. Inversion layer (isothermal near tropopause to about 20 km)
               (A). Upper stratosphere: more UV radiation available to warm less mass of air resulting
                       in a higher temperature.
               (B). Lower stratosphere: less UV radiation available to warm more mass of air resulting in
                      a lower temperature.
          C. Stratopause: 50 km (30 mile) with a peak temperature of -2 ^oC (-28 ^oF).
          D. Ozone: Maximum concentration at 25 km.
    (3). Mesosphere
          A. Regular lapse rate.
          B. Mesopause: 80 Km (50 miles)
              Minimum temperature: the coldest layer due to the lack of UV absorption by ozone.
    (4). Thermosphere
           Inversion and isothermal.
    (5). Ionosphere: 80 km to 700 km.
          A. D,E,F layers
          B. Radio communication.
          C. Atoms, free electrons.
7. Composition of the atmosphere
    (1). Homosphere
          A. Ground to 80 km (Mesopause).
          B. Major constituents of the atmosphere remain unchanged.
          C. Ozone, dust, and water vapor vary greatly.
    (2). Heterosphere: 80 -700 km, all ions.

8. Diurnal variation
          (1). The lowest air temperature: just before sunrise.
          (2). The highest air temperature: 2 pm at 2 meter height.
          (3). Air is directly warmeded up by the terrestrial radiation.

9. Isotherm: line of equal air temperature.

10. Heat Index (Apparent Temperature):

Please click the following URL and ignore other links

(references only)

http://www.wrh.noaa.gov/lox/heat.php

http://www.crh.noaa.gov/pub/heat.php

http://en.wikipedia.org/wiki/Heat#Thermal_energy