Estimating Altitude of Water Cloud Base

Français This lab has been used by various high school teachers, and was provided by Carolyn Green.

The method calculates the Lifting Condensation Level, which is the level at which condensation -- formation of water droplets -- would occur if a parcel of air near the surface is lifted upwards. The method will only work for a limited number of low-level clouds, but may be useful in deciding between low- and mid-level clouds.

Grade Level/Subject/Class Time:

• Grade 6th, 7th, 8th & 9th /Science,Math/ One 50 minute class period.

Applicable National Standards:

• Science, national and VA: 4.1, 4.6, 5.1, 6.1, ES.13 ; Mathematics, national and VA: 5.11

MATERIALS:

• Aluminum can, stirring rod, ice cube, thermometer.

Procedures

1. Record air temperature with thermometer.
2. Add a cube of ice to the can half full of water. Insert the thermometer and stir with stirring rod. Note the temperature as soon as mist appears.
3. Remove the ice and stir. Record temperature as soon as mist disappears.
4. Calculate average of #2 and #3. This is the dew point temperature. Record dew point temperature.
5. Determine the altitude of the clouds be following these steps:
   1. Record the temperature and dew point temperature at ground level.
   2. For every 100 meters in altitude the temperature drops one degree C and the dewpoint drops 0.2 degree C.
   3. Construct a chart like the one started here. (This is an example. These numbers are not real!!!)
   4. Continue until the numbers match. At that point draw a cloud.

Example

Altitude (meters)	Temperature (deg C)	Dew Point (deg C)
400	18	18 = Cloud
300	19	18.2
200	20	18.4
100	21	18.6
Ground	22	18.8

S'COOL What to Observe Report Form Glossary

Last Updated: by Carolyn J. Green.