DEPARTMENT OF GEOSCIENCES                  NAME_________________________

SAN FRANCISCO STATE UNIV                                Meteorology 201


In-class Lab Assignment 3

(100 pts)

Due Thursday May 5, 2011



Purpose of this Assignment:

  • To explore parcel theory more deeply;
  • To introduce students to the analysis of soundings on Skew T/log P diagrams in an operational setting;
  • To give students an opportunity to visualize how instability manifests itself in the morning environment in severe weather settings;
  • To show students how severe weather meteorologists estimate afternoon instability by transforming the morning sounding;
  • To show students how to evaluate the instability graphically, and computationally;
  • To introduce students to the finite difference approximation of summation (integration) graphically and computationally.

Course Learning Objectives Met: 2, 5 and 6


1.      Determine the morning stability at KOUN (Norman, OK) from the morning sounding for 1200 UTC 3 May 1999 (attached).

Estimate the height (in millibars) of the Lifting Condensation Level, Level of Free Convection, 500 mb Lifted Index, Equilibrium Level and determine if the sounding is unstable, stable or conditionally unstable with respect to a SURFACE LIFTED PARCEL. Be sure to indicate the parcel ascent curve, LCL, LFC and EL right on the diagram.(30 points)


2.      Estimate the afternoon stability at KOUN (Norman, OK) from the morning sounding for 1200 UTC 3 May 1999 (second copy).  Estimate the Convective Temperature, Convective Condensation Level and determine if the sounding is potentially unstable.  Indicate the CT, CCL, parcel ascent curve, positive area on sounding (CAPE) (shaded red), and negative area on sounding (CINH) (shaded blue).(30 points)


3.      Calculate the CAPE from the morning sounding using the method discussed in class. You'll be approximating the CAPE by summing up the indidividual contributions of layers approximately 1500 m thick. The table below should get you started. (Started in class) (30 points)


Pressure (mb)

Elevation AGL (m)

Temp Env (K) Temp Parcel (K) Diff

(LFC) ~700















(EL) 240




Elevations of pressure surfaces for KOUN 12 UTC 5/3/99



4.      Using the results from (3) above, calculate the maximum vertical velocity at the EL in the morning.  (Started in class) (10 points)


KOUN Sounding 12 UYC 3 May 1999


KOUN Sounding and Hodograph, 12 UTC 3 May 1999 (click on sounding to get larger version)