2. Day 28 Investigation 6 part 2 Evaporation and Humidity

3. Vocabulary Water vapor is the gaseous phase of water Evaporation is when liquid water changes from a liquid to gas (water vapor) Humidity is water vapor in the air When it is humid = a lot of water vapor in the air

4. Saturated When air contains as much water vapor as it can Only a little bit of water vapor to saturate cold air Takes a lot of water vapor to saturate warm air

5. Relative Humidity How meteorologist often describe the amount of water vapor in the air Measured in percentages Compares the amount of water vapor in the air to the amount needed to saturate the air

6. Relative Humidity = 100% Would things dry up very fast? The air is saturated with water vapor Air can absorb any more water No evaporation occurs

7. Into the Air Water vapor gets into the air several ways – Liquid water can evaporate when it absorbs energy Radiation Conduction

8. Transpiration Water leaves plants as vapor Condensation on the side of a terrarium

9. Not just plants All terrestrial animals exhale water vapor when they breathe Also from: – Fires – Internal combustion engines – Volcanic eruptions

10. Hygrometer Measure relative humidity Measures the water vapor in the air and compares that to the amount needed to saturate the air Relative Humidity as a percent

11. STUDENT SHEET COMPLETE PG. 31 “RELATIVE HUMIDITY” IN YOUR LAB BOOK.

12. HOMEWORK OPEN TO PAGE 33 “RESPONSE SHEET - WATER IN THE AIR” IN YOUR LAB BOOK. COMPLETE FOR HOMEWORK.