SAN FRANCISCO STATE UNIVERSITY                         METEOROLOGY 403         

DEPARTMENT OF GEOSCIENCES                                  Fall 2004

                    

Homework No. 2

Due Thursday September 16, 2004

 

Reading:           Bottom of page 84 to 91 (Translation and Divergence)

                        pp 181 (Thermal Wind) to 190

 

Lay out all steps.  Number all equations sequentially.  Maps/charts are to be neatly analyzed using correct color conventions. 

 

1.      Attached find the sounding for KMIA (Miami, FL) for 12 UTC 7 September 2004 and that for 12 UTC 24 May 2004 for KOUN (Oklahoma City – really, Oklahoma University Norman Campus) plotted on a Skew-T/Ln P Diagram.

 

         Since the single largest source of error in the forecast contest last for Tuesday was the precipitation amount for Miami, it is clear that only I clearly caught the brieferÕs error in evaluating the Miami sounding.  This is not a Òpile onÓ for me onto Chris.  We all make errors in the briefings. 

 

         However, several you made the comment on the evaluations that the briefer was nervous (as you all will be) partially due to my questions.  But the point of the questions is not to make the briefer nervous but to ask questions about logical inconsistencies, errors etc. that could lead the briefing audience astray.  In this case, you all assumed that since Chris was the briefer, he was Òthe authorityÓ and his observations should not be questioned. 

 

         Unless each student who listened to the briefing made mental note to the errors he made with respect to the KMIA sounding evaluation, then you ALL made the same error (hence, underscoring the fact that by pointing this out I am not trying to make Chris uncomfortable, but point out that each of you who did not forecast precip for Miami would have made the same errors as briefers).

 

         The choking sound you heard during the briefing was my response when the briefer referred to the KMIA sounding as an example of a "Loaded Gun sounding" and when he did not underscore the risk for thunderstorms there.

 

(a)           Examine the two soundings and describe why the KOUN sounding is indeed an example of a "loaded gun" while that for KMIA is not.  (Before you attempt to do that, please write down the definition of a "loaded gun" sounding.)

 

(b)          Evaluate the KMIA sounding for convective potential (only due to parcel lift—you donÕt have to transform the sounding for afternoon heating)

 

 

2.      Write out the general vector expression for the three dimensional wind in rectangular coordinates?  In natural coordinates?

 

3.      Write out the equation of  motion in natural coordinates (Eq. 4.1.108 and 109).  Assume that it is early morning, and winds are calm.  How is the above equation set simplified?  (In other words, simply on the basis of these conditions).