Lab 8: CLOUD observation and SKEW-T diagrams
Part I: Skew-T analysis of weather balloon soundings
1.
On each of the 4 attached skew-T diagrams from this morning, draw the line of a lifted parcel
from the surface all the way through the atmosphere. Be sure that you follow the correct lapse rates
based on saturation-status. If the dewpoint and temperature change rapidly very near the surface
(lowest 25 mb), use the mixing ratio line and temperature that corresponds to the air immediately above
this thin surface layer.
2.
On each diagram, mark the location of the Lifting Condensation Level (LCL), the Freezing Level
(FRZL), and the -20 C Level. If the sounding includes a region of instability, mark the Level of Free
Convection (LFC), the Equilibrium Level (EL), and the approx. Maximum parcel Height (MPL). If the
sounding permits, shade in any areas of CAPE and CIN.
3.
For any levels marked on the graphs in #2 (LCL, FRZL,-20 C, LFC, EL, or MPL), use the graphs and
equation P=P0exp(-z/8100) to find the level altitude in meters and feet.
4.
For each sounding, right one paragraph describing what weather conditions may be likely this
afternoon at this location and what at levels clouds (if any) may be likely to form. For cloud formation,
discuss what classification of cloud is likely based on any regions of instability or high relative humidity.
Part II: Local sky observation
Step outside and move to the middle of the quad, unless otherwise instructed. Survey the sky
carefully. Use the compass to gather your directional bearings, remember that the magnetic compass
offset is 12 degrees. Describe the appearance of the sky and any clouds that may be visible. Be sure to
include the following, if applicable.

Color of the sky

Percentage covered by clouds (approx.)

Any visible contrails

Direction of cloud movement (use provided compass)

Direction and speed of surface winds

Detailed description and classification of any visible clouds

Apparent phase of clouds

Unusual optical phenomena
Part III: Satellite and surface comparison of clouds
1.
Use computer search resources to find the location where each of the 4 soundings was taken.
2.
Use the available satellite imagery links to describe the general appearance or lack of clouds
near these four locations at the present time. Be sure to describe texture and movement of clouds if
they are visible near the station. If you have trouble finding an appropriate link, please ask for
assistance.
3.
Use the course weather links to find the observational description of cloud heights from these
four locations. If you have trouble finding an appropriate link, please ask for assistance.
4.
How do the results from part I compare with your results from part II and III? Do you think the
soundings provided good, fair, or poor perspective on the character of clouds and weather likely to
occur later in the day? If fair or poor, what do you think might have caused the shortcomings?