Atmospheric Sciences 211

Midterm exam 1

Tuesday, January 23, 2001



(1) It is often observed that delicate plants like wildflowers, which need plenty
     of moisture, grow on north facing slopes, while plants like cactus and sagebrush,
     which need very little moisture, tend to grow on south facing slopes.  Explain.
      (10 points)

(2) In a make-believe solar system there is a planet similar to the Earth except
     that its orbit about its sun is highly elliptical.  At its closest approach to its
     sun the distance is 1 A.U. (the same as Earth's mean distance from its sun), but
     its orbit ranges out as far as 4 A.U.
     (a) Compare the relative amounts of solar radiation that it receives at the
          outermost and innermost points in its orbit.
     (b) If the albedo of the planet is fixed, and if the planet is always in radiative
          equilibrium, by what fraction does its effective radiating temperature vary as it
          orbits its sun?
    (c) In making this comparison, should you use the Fahrenheit, the Celsius, or the
         Kelvin temperature scale?
     (10 points; 4, 4, 2)

(3) (a) Venus is closer to the sun than the Earth, yet it has a lower effective
            radiating temperature than the Earth does.  Explain.
     (b) Although Venus has a lower effective temperature than Earth, its surface
           temperature is much higher.  Explain.
     (c) The brightness of Venus in the night sky bears no relation to its effective
           radiating temperature.  Explain.
     (15 points; 5, 5, 5)

(4) The United States experiences its coldest weather at the time of year when the
      earth is closest to the sun.  Explain this apparent paradox. (10 points)

(5) (a) When an infrared radiometer like the one we examined in class is pointed
           upward at clear sky it reads a lower temperature than when it is pointed at a
           cloud layer.  Explain.
      (b) Is the radiometer likely to read higher when pointed at a high cloud layer
           or a low cloud layer?
      (c) Are there any conditions under which it could read higher when pointed
           upward at a cloud layer than when pointed downward toward the ground?
      (10 points; 4, 4, 2)

(6) On a summer afternoon, the vertical temperature profiles at Seattle and Yakima
      (located on the eastern side of the Cascades) are identical above the 1-kilometer
      level, where the temperature at both locations is 20 C (68°F).  Down close to
      sea-level, the temperature at Seattle, which is experiencing a seabreeze from
      Puget Sound is also 20 C, whereas at Yakima it is 28 C.
      (a) What are the lapse rates (expressed in degrees C per kilometer) at the two locations?
      (b) If hot air balloons were launched at the two cities, which one would require more
           heating in order to enable it to rise to the 1 km level?
      (c) What is the ratio of the amounts of heating required at the two locations?
           [Hint: assume that due to expansion, the air in the balloon would cool at a rate of
           10°C per kilometer if it weren't heated.]
      (10 points; 4, 4, 2)

(7) If summer rainfall is below normal for an extended period of time, vegetation
      tends to wilt or die, As the vegetation wilts or dies, less moisture evaporates
      from the underlying soil.  If there's less evaporation, the air is likely to be
      drier and weather systems are likely to produce less rain when they pass through.
      Is this a positive or a negative feedback loop?  Explain your answer.
      (10 points)

(8) Name the four major components of the Earth System and give one example of how
      each of the four components is influenced by one of the other components.
      (10 points)

(9)  Match the following climate statistics with the locations. Consider the latitudes carefully.  (5 points)

A  Tumaco, Colombia (2°N)   (  )
B  Darwin, Australia (12°S) (  )
C  Bangkok, Thailand (14°N) (  )
D  Calcutta, India (23°N)   (  )

        JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
1) T(°F) 84   84   84   84   82   81   79   81   82   86   86   84
   r(mm)386  312  254   97   15    3   --    3   13   51  119  239

2) T(°F) 79   82   84   86   86   84   84   84   82   82   81   79
   r(mm)  5   28   28   58  132  152  175  234  356  252   46    3

3) T(°F) 64   70   79   84   86   84   82   82   82   81   72   64
   r(mm) 10   28   36   21  127  284  307  292  228  109   13    5

4) T(°F) 79   79   79   80   80   79   79   79   79   79   79   79
   r(mm)428  297  243  370  441  304  195  185  185  150  124  177

(10)  Match the following climate statistics with the locations  (5 points)
A  Perth, Australia (32°S) west coast   (  )
B  San Diego, CA (32°N) west coast      (  )
C  Tokyo, Japan (36°N) east coast       (  )
E  Mexico City (19°N) alt. 7000 ft      (  )

        JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
1) T(°F) 56   58   58   62   63   66   70   72   70   66   62   58
   r(mm) 48   38   39   20    4    1   --    2    3    9   31   44

2) T(°F) 39   39   44   56   62   70   75   79   74   62   52   43
   r(mm) 48   63  106  135  147  165  142  153  234  208   97   56

3) T(°F) 74   74   72   66   62   58   56   56   58   64   68   64
   r(mm)  8   10   20   43  130  181  170  145   88   56   21   13

4) T(°F) 54   56   61   64   68   66   65   65   64   61   58   56
   r(mm)  5    8   13   18   48  104  114  109  104   40   13    8
 


(11) Match the following climate statistics with the locations  (5 points)

A  Seattle, WA (47°N)                 (  )
B  Fairbanks, AL (65°N) inland        (  )
C  Bismarck ND (47°N) mid-continent   (  )
E  San Francisco, CA (38°N) coastal   (  )

        JAN  FEB  MAR  APR  MAY  JUN  JUL  AUG  SEP  OCT  NOV  DEC
1) T(°F) 39   41   44   50   56   60   64   64   59   52   46   43
   r(mm)125   97   79   61   46   33   15   18   44   71  122  140

2) T(°F)  8   14   25   43   54   64   72   70   58   46   28   16
   r(mm) 10   10   20   31   51   86   53   43   31   23   15   10

3) T(°F) 52   54   54   56   58   59   59   59   62   61   58   52
   r(mm)101   88   96   33   13    3   --   --    5   18   33  104

4) T(°F)-12   -2   12   28   46   59   61   56   44   25    3  -10
   r(mm) 23   13   10    8   18   35   45   55   27   23   15   13