2. Humidity is the amount of water vapor in the air. It is measured in grams of water vapor per kilogram of air.

3. Temperature Degrees Celsius Vapor (g) per Kilogram of Dry Air 5088.12 4049.81 3027.69 2014.85 107.76

4. Ancient History – 1 st quarter What do you remember about solubility? Saturated Unsaturated Supersaturated Any point on the line represents saturation.

5. What does your body do to cool you off when you are too hot? Why does sweating work?

6. Evaporation = Liquid Water → Water Vapor Does this process require or release heat energy? Requires

8. Fun Fact What is the only animal that sweats through its skin like we do?

12. Why do we feel cooler on a hot day if the air is dry?

13. Why do we feel hotter on a cool day if the air is humid?

14. Weather feels oppressive at 70% relative humidity.

15. Fun Fact What is another effect of high humidity?

16. An Old Fashioned Hygrometer

17. Hair Hygrometer You Can Make Yourself

18. Percent of water that the air is holding relative to the maximum amount that it can hold at its current temperature. The actual water vapor present compared to how much could be present at that temperature.

19. 1. Which represents the warmest air? 2. Which represents the coldest air? 3. Which 3 have the same humidity? 4. Which one has the highest humidity? 5. Which one has the highest RELATIVE humidity? 6. Which on has the lowest RELATIVE humidity? A B C D C or D A A, B and C D A C

20. Hygrometer

21. How would your foot feel if you were wearing a wet sock? COLD! DEPRESSED

22. A Dry Day… A lot of moisture will evaporate The wet bulb thermometer cools. The wet bulb temperature drops a lot. It gets depressed! 8°C 20°C

23. Wet Bulb Depression The difference between the dry and the wet bulb temperature readings is called the wet bulb depression because the wet bulb thermometer’s temperature is lowered, or depressed.

25. A Humid Day… Since the air is humid, only a little moisture can evaporate. The wet bulb will not be much cooler than the dry bulb. It’s not as depressed! 14°C 20°C

27. Dry-bulb temperature is your air temperature. 20 °C

28. The Wet Bulb Depression is shown across the top of the chart. 8°C 20°C 20-8=12 Calculate the wet bulb depression.

29. 8°C 20°C 20-8=12 Relative Humidity = 11% DRY DAY

30. 14°C 20°C 20-14=6 HUMID DAY Relative Humidity = 51%

31. Try These. Dry Bulb Wet Bulb Wet Bulb Depression RelativeHumidity 26°C 20 °C 6 °C 5 °C 12 °C 8 °C 18 °C 17 °C 14 °C 0 °C -3 °C 58% 86% 58% 91% 100% 46% 1 °C 4 °C 6 °C 0°C 3 °C