DEPARTMENT OF GEOSCIENCES                               Name____________________    

San Francisco State University                                         April 8, 2009                                                                                                                                                                                      Spring 2009

 

Synoptic Metr 201 Quiz #1 Key

100 pts.

(Test will be collected at 10:45 AM)

 

A.  Definitions.  (5 points each for a total of 25 points in this section).

 

(a) Lifting Condensation Level -- the elevation (in millibars or feet/km) to which an air parcel must be lofted in order for its saturation mixing ratio (determined by its actual temperature and the saturation mixing ratio line upon which it resides) is decreased to the actual mixing ratio (determined by the saturation mixing ratio line passing through the surface dew point). At this elevation or level, the relative humidity of the ascending parcel will be 100% and a cloud base will be found.

 

(b) Level of Free Convection -- the elevation (in millibars or feet/km) to which an air parcel must be lofted above which its temperature will be warmer than that of the air surrounding it at the same elevation. Above this elevation the parcel no longer needs to be forced upwards, as it will freely convect (be spontaneously buoyant).

 

(c)         The study of the development of and evolution of atmospheric motions and circulation systems as solutions of the fundamental equations of hydrodynamics or other systems of equations appropriate to special situations is the definition of _____dynamic meteorology _______________

 

(d)         A contour of constant pressure is known as an _______ isobar _____________

 

 

(f)  Synoptic Meteorology – The study and analysis of weather systems based upon analyses of a set and/or series of charts upon which a synopsis of weather information is displayed and upon application of the principles of physical and dynamic meteorology.

 

 

B.      Units. (3 pts each for a total of 12 pts)

         Provide the units (metric) used conventionally for the following

        

         V                                           _______m s-1____________________

 

         u                                           ________m s-1__________________

 

acceleration due to gravity                 ________ m s-2_______________

 

         w                                          ________cm s-1______________

 

 

 

 

C. Sounding (4 pts each for a total of 28 points in this section).

 

Examine the sounding given below.  Note the locations given at A, B, C, D, E and F. Two copies of are provided.  One of the copies has only the standard parcel ascent curve for this case.  The other copy has colored areas (red and blue) added.

Sounding with No CAPE areas indicated
 


Sounding with No CAPE areas indicated

 

1.  This sounding is (choose the correct answer by circling your choice)

 

(a)  Absolutely stable

(b)  Absolutely unstable

(c)  Conditionally unstable

(d)  None of the above

 

2.  The line (solid red) indicated by the letter A is the

 

(a)  Parcel Ascent Curve

(b)  Dew Point Temperature Lapse Rate

(c)  Environmental Lapse Rate

(d)  Condensation Lapse Rate

(e)  Dry Adiabatic Lapse Rate

 

3.  The line (dashed red) indicated by the letter B is the

 

(a)  Parcel Ascent Curve

(b)  Dew Point Temperature Lapse Rate

(c)  Environmental Lapse Rate

(d)  Condensation Lapse Rate

(e)  Dry Adiabatic Lapse Rate

 

4.  The level indicated by the letter C is the

 

(a)  Equilibrium Level

(b) Lifting Condensation Level

(c)  Level of Free Convection

(d)  Equilibrium Level

(e)  Convective Temperature

 

5.  The level indicated by the letter D is the

 

(a)  Equilibrium Level

(b)  Lifting Condensation Level

(c)  Level of Free Convection

(d)  Equilibrium Level

(e)  Convective Temperature

 

6.  The area colored blue indicated by the letter E is

 

(a)  the layer in which the lofted parcel is warmer than the surrounding air at the same elevation

(b) the layer in which the lofted parcel is colder than the surrounding air at the same elevation

(c)  proportional to the Convective Available Potential Energy (CAPE)

(d)  the layer through which the air parcel will be freely buoyant (will loft without any forcing)

(e) Choices (a), (c) and (d) are correct.

 

7.  The area colored red indicated by the letter F is

 

(a)  the layer in which the lofted parcel is warmer than the surrounding air at the same elevation

(b) the layer in which the lofted parcel is colder than the surrounding air at the same elevation

(c)  proportional to the Convective Available Potential Energy (CAPE)

(d)  the layer through which the air parcel will be freely buoyant (will loft without any forcing)

(e) Choices (a), (c) and (d) are correct.

 

 

 

D.  Short Answer.   (Answer below or on back in complete sentences, with subject, verb and object in each sentence, please)  (17.5 pts each for a total of 35 points in this section)

 

1.     The philosophical underpinning of sounding analysis is something called “parcel theory.”  In a few sentences, briefly describe what is meant by “parcel theory.”

 

Parcel theory is centered on the concept that there is one air parcel at the surface that is assumed to have the same temperature and dewpoint of the environment at the surfac. This parcel isthen lifted relative to the environmental air.Parcel theory has its limitations, since it is difficult to define how large or small a parcel really is and what mechanisms exist that selectively lift the small parcel and not the entire atmospheric layer. In addition, parcel theory fails to accomodate the fact that considerable entrainment of surrounding air occurs as buoyant plumes develop. However, parcel theory has been shown to be successful in explaining thunderstorm development.




2.     Thunderstorms can be severe or non-severe.  What distinguishes severe thunderstorms from ordinary non-severe thunderstorms?

 

A thunderstorm (sometimes referred to as a "convective storm" is defined as SEVERE if it produces straight-line winds 50 knots or greater (57 mph) and/or hail 3/4" in diameter or larger and./or tornadoes