FOR THIS LAB, YOU WILL NEED TO PRINT THE QUESTION SHEET, THE ANSWER SHEET, AND ALL TABLES AND FIGURES.
Terms: Relative Humidity, Water Vapor Pressure, Dewpoint, Adiabatic Lapse Rates
Exercises: Determine Relative Humidity with
Sling Psychrometers
Solve "Air over the Mountain" Problem
Calculate Thunderstorm Rainfall
Questions: (28 Points)
1. a. Use the sling psychrometer and Figures One and Two to determine the relative humidities and dew points of two locations. (At least one of the locations should be outside).(6)
b. What happens to the thermometers when the
sling psychrometer is spun? (2)
c.. How do these changes make it possible to measure
relative humidity?
2. Complete Chart in Figure Three, using the charts in Figures One and Two (2)
3. Define dewpoint. (2)
4. Air over the mountain: Figure Four (3)
SHOW ALL WORK Assume a dewpoint temp of 12 deg C
a. Figure the elevation that the air parcel reaches
dewpoint using the dry adiabatic lapse rate (10
degrees per 1000 meters).
b. Using the wet adiabatic rate, (6 degrees per
1000 meters) now that the parcel is saturated,
figure the temperature of
the air parcel at the mountain peak. (Assume that the elevation of the
peak is 2400 m).
c. Assuming that the air parcel has released all
or most of its moisture on the windward side of the mountain,
use the dry adiabatic lapse
rate and figure the temperature of the air parcel at 600 meters on the
leeward
slope.
*Remember that when air rises, it cools,
and when it sinks, it warms.*
5. Compare the temperature at 600 meters on the windward side with the
temperature on the leeward side
at the same altitude.
What is the difference in temperature?
(1)
6. Describe the difference in conditions (what you see in vegetation
and what you feel in temperature and
humidity) between the windward and leedward sides
of the mountain. (Imagine driving through the Basin
and Range into the Midlatitude Rain Forests of N.
California, Oregon and Washington.) (2)
7. Thunderstorm Rainfall: The cloudburst of a large cumulonimbus cloud can produce rainfall at a rate exceeding 5 inches per hour. Table One shows the rainfall intensity of a brief thunderstorm at Hays, Kansas, in early August. Rainfall was recorded for each five minute period. The Table gives rainfall intensity records for ten five-minute periods.
a)Plot these data as a bar graph on Figure Five, using the left-hand scale. (5)
b) Calculate the amount (depth, inches) that fell in each 5 minute period.
(Divide intensity by 12). Enter in the second column. In the third column,
cumulate the depths and plot them to make a step graph, using the depth
scale on the right-hand side of the graph. ("Cumulate" means to add each
new value to the sum of the previous ones). The final entry will be the
total depth of rainfall during the storm. (5)
