DEPARTMENT OF GEOSCIENCES             Name ____________________

San Francisco State University                      April 21, 2011                                   

Metr 201, Spring 2011

Monteverdi Quiz #2 Key

100 pts.

Answer in complete sentences under the question or on the back of the exam.  Please write legibly.


A.   U.S.  Radar Coverage.  (10 points each for a total of 20 points in this section).


Refer to Figure 1 at the back of the test.


1.    The overlapping white circles on the map of the United States indicate what?  (10 pts)


 The white regions are areas with radar coverage by the National Weather Service's Doppler Radar network.







2.    Why is there a grey area shown in eastern California extending into central Nevada? (10 pts)


 This is a region without radar coverage, mostly because of high mountains blocking radar beams.






B.   Radar Interpretation.  (30 points in this section). Refer to Figure 2 at the rear of the test , which shows the hook echo associated with the Springfield-Wilson, North Carolina tornadoes.


1.    The arrow labeled A refers to a bulbous extension of the hook. What is that bulbous extension called (5 pts) and what is its significance (10 pts)?

The arrow labeled A refers to a so-called "Debris Bulb." It represents radar echoes or returns coming from debris lofted from a tornado.


2.    The arrow labeled B refers to a red circle from which a line with time intervals are annotated extends. What does that circle represent (its name) (5 pts) and what is its significance? (10 pts)?

  The red circle refers to the location of a tornado vortex signature (TVS). This indicates that the radar has located a forming tornado or a tornado in progress.






C.   Satellite Interpretation.  Examine Figures 3 and 4 at the rear of the test, and note the locations shown at A,  B and C on both images. (35 points)


1.    Which of the three locations has the clouds that are most likely be towering the highest in the troposphere and why  (use both images for this)?  (15 pts)





 The clouds at location B have the coldest tops (as indicated by the blue colors on the infrared imagery).  We make the assumption that these clouds are towering from the ground to the level in the atmosphere at which the temperatures are very cold, which is almost always at high elevation. Also, the visible image shows the brightest white in this area, suggesting thick clouds reflecting much of the incident solar radiation. Finally, the visible image suggests shadowing, which occurs when clouds are towering. The combination of all of these suggests the possiblity of thick clouds, possibly cumulonimbus, which often are associated with heavy precipitation.









2.    Here are the three cloud types that are occurring at either location A, B and C:  stratus, altocumulus, and cumulonimbus.  Insert these cloud names at their most likely location.  You may only use the cloud type once: (15 pts)



Location A __altocumulus


Location B __cumulonimbus


Location C _stratus





     3.  The temperature of the cloud tops at location B is approximately (5 pts)


(a)    10C

(b)   20C

(c)   -10C

(d)   -55C

(e)    0C


D.      Units. (3 pts each for a total of 15 pts)

         Provide the units used conventionally for the following:


                     ____ Ko *    


                     ______Co___or Fo___________  


            ______m s-2_______________**


                     ____ cm s-1__________________


                    ____m s-2__________________

*= Theta


**PGA = Pressure Gradient Acceleration



Figure 1:  Radar Analysis for 1749 UTC 11 February 2005



Figure 2:  Reflectivity from the Tulsa Radar for 2026 UTC 4/16/2011


Figure 3:  Visible Satellite Image, 2145 UTC 14 April 2011

Figure 4:  Enhanced Infrared Satellite Image, 2145 UTC 14 April 2011