1. 6.3: Finding Moisture in the Atmosphere
Unit 6: Meteorology
February 28, 2012
Sanders

2. Relative Humidity

3. Relative Humidity
Relative humidity is the amount of water vapor in the air compared to the amount of water vapor the air can hold at capacity.

4. Relative Humidity
Relative humidity is the amount of water vapor in the air compared to the amount of water vapor the air can hold at capacity.
Changes in temperature or the amount of water vapor in the air cause the relative humidity to change.

5. Relative Humidity

6. Relative Humidity
Relative humidity is the amount of humidity in the air and the air temperature affect comfort.

7. Relative Humidity
Relative humidity is the amount of humidity in the air and the air temperature affect comfort.
Saturated air cannot accept more moisture, like from sweat.

8. Sling Psychrometer

9. Sling Psychrometer
An instrument used to find relative humidity is made of 2 thermometers

10. Sling Psychrometer
An instrument used to find relative humidity is made of 2 thermometers
One has a wick or sock on the bulb

11. Sling Psychrometer
An instrument used to find relative humidity is made of 2 thermometers
One has a wick or sock on the bulb
Spinning it forces evaporation

12. Finding Moisture
Page 12, Earth Science Reference Table

13. Finding Moisture
To find relative humidity, you need to know the difference in temperature of the dry and wet thermometers, the temperature of the dry thermometer, and a humidity chart.
Page 12, Earth Science Reference Table

14. A psychrometer was spun

15. A psychrometer was spun
The dry bulb reads 26.

16. A psychrometer was spun
The dry bulb reads 26.

17. A psychrometer was spun
The dry bulb reads 26.
The wet bulb reads 21.

18. Find the dry bulb temperature

19. Find the dry bulb temperature

20. Find the dry bulb temperature What’s the wet-bulb temperature?
Subtract the wet bulb temp from the dry bulb temp

21. Subtract 21 from 26

22. Subtract 21 from 26
The differences is 5

23. Subtract 21 from 26
The differences is 5

24. Subtract 21 from 26
The differences is 5

25. Subtract 21 from 26
The differences is 5

26. Subtract 21 from 26
The differences is 5

27. Dewpoint

28. Dewpoint
Dewpoint is the temperature when atmospheric water vapor condenses to form water.

29. Dewpoint
Dewpoint is the temperature when atmospheric water vapor condenses to form water.
At left, dew settled on a spider web.

30. A psychrometer was spun

31. A psychrometer was spun
The dry bulb reads 26.

32. A psychrometer was spun
The dry bulb reads 26.
The wet bulb reads 21.

33. A psychrometer was spun
The dry bulb reads 26.
The wet bulb reads 21.
We already know to look for the difference.