Lab #____: Relative Humidity & Dew Point Temperature
Problem: How do we use a sling psychrometer to determine the relative humidity of air.
Vocabulary: - Humidity - Dew Point - Water Vapor - Saturated – Psychrometer
- Dry Bulb - Wet Bulb
Procedures:
1. Dip the sling psychrometer in a small amount of water and swing it for 1-2 minutes.
2. Record both the wet and dry bulb temperatures and record measurements in data table
#1. **Measurements must be in ˚C, otherwise use ESRT pg 13 to convert ˚F to ˚C.
3. Calculate the difference and record in data table #1.
4. Use the charts provided on ESRT pg 12 to complete the data table.
EXAMPLE:
Wet Bulb: 1˚C
Dry bulb: 4˚C
Difference: 3˚C
Relative Humidity: ___
Data Table #1
Measurement
Wet Bulb
Dry Bulb
Difference
Relative Humidity
Dew Point Temp.
Trial #1
Trial #2
Trial #3
Questions:
1. What is the relative humidity when the wet and dry bulb temperatures are equal?
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2. Explain what happens to the relative humidity value as the difference between air
temperature and dew point temperature increases.
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3. Explain how sweat cools you on a hot day?
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4. Why is the wet bulb temperature always the lower measure of the two?
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5. Is the air saturated today? How do you know?
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6. Describe the relationship between air temperature and the ability for the air to hold
moisture.
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Conclusion:
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