School Improvement in Maryland
the Copper Basin Problem  

Student Section

How Does the Amount of Vegetation Affect Relative Humidity and Temperature?
Student Investigation 3:

Organisms lose water faster in an atmosphere with lower humidity than in an atmosphere with higher humidity. The barren Copper Basin had much less vegetation than the forested area surrounding it. Two abiotic factors, temperature and relative humidity, might be very different in each area. We will measure and compare the temperature and relative humidity in three microenvironments at different heights and compare the results. We can use the results to predict if the barren land in the Copper Basin could have caused changes to the micro-climate in that area.

Problem:

Does the amount of plant life affect the relative humidity and temperature of an environment?

Materials:
  • 3 watches/clocks/timers
  • 3 metersticks
  • 3 thermometers (dry)
  • 3 thermometers (with cotton sleeve over bulb end)
  • 3 screw top jars of 30-50 mL distilled water
  • 3 pieces of stiff cardboard for fanning
  • 3 shade devices
  • Table of Relative Humidity
Procedure:
  1. Predict differences that will be found in the 3 different environments.
  2. Divide the team into 3 pairs of students. Each pair will measure the temperature in one of the three environments at 0 cm, 10 cm, 90 cm, and 150 cm. The 3 environments are:
    • the woods (dense cover of plants)
    • the edge of the field (thicket or shrubby area), and
    • the middle of the soccer field (barren ground).
  3. One person in each team should record the data. Teams should synchronize their timers. Write the synchronized times on a chart. All measurements should be made at the same times. Schedule at least 10 minutes between readings.
  4. Wet the cotton sleeve of one thermometer with distilled water. This should be done before each reading.
  5. Read both thermometers at the same time. Position the thermometers at least 2 minutes before a reading so that the temperature can stabilize. Use the shade device to shield the thermometer from the direct rays of the sun. Fan the thermometers with the stiff cardboard for 2 minutes, then read the 2 temperatures and record your readings. Repeat this procedure at each height.
  6. Using your measurements and the relative humidity chart, determine the relative humidity. Relative humidity is the percent of water vapor actually in the air at any given temperature compared to the amount of water vapor the air could hold at that temperature.
  7. Share results with the other teams.
 

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