Chapter 23 Section 1 Chapter 23 Section 1 Review Page 580Review Page 580

1. Explain how most 1. Explain how most water vapor enters the water vapor enters the air.air.

• When water molecules absorb When water molecules absorb heat energy they move so heat energy they move so rapidly they escape the liquid rapidly they escape the liquid and enter the air as water vapor.and enter the air as water vapor.

Water Vapor satellite imageWater Vapor satellite image

2. Identify the principal 2. Identify the principal source from which most source from which most water vapor enters the water vapor enters the atmosphere.atmosphere.

• The oceans near the equatorThe oceans near the equator

3. Identify the process by 3. Identify the process by which ice changes which ice changes directly into a gas.directly into a gas.

• Sublimation (have you ever seen Sublimation (have you ever seen dry ice?)dry ice?)

SublimationSublimation

4. Define humidity.4. Define humidity.

•Humidity is water vapor in Humidity is water vapor in the atmospherethe atmosphere..

5. Compare relative 5. Compare relative humidity with absolute humidity with absolute humidity.humidity.

• Absolute humidity is the mass of water Absolute humidity is the mass of water per unit volume of air and represents a per unit volume of air and represents a measure of the actual amount of water measure of the actual amount of water in the air (squeeze a wet sponge).in the air (squeeze a wet sponge).

• Relative humidity is the ratio of water Relative humidity is the ratio of water vapor in the air compared to how much vapor in the air compared to how much it could hold at a given temperature it could hold at a given temperature (how full is the sponge?).(how full is the sponge?).

6. 6. Describe what happens Describe what happens when the temperature of when the temperature of air decreases to the dew air decreases to the dew point or below the dew point or below the dew point.point.

• When temperature decreases the When temperature decreases the rate of condensation increases, rate of condensation increases, and the rate of evaporation and the rate of evaporation decreases. At the dew point the decreases. At the dew point the rate of condensation and rate of condensation and evaporation are equal. Below the evaporation are equal. Below the dew point, condensation occurs dew point, condensation occurs and visible water droplets form on and visible water droplets form on surfaces.surfaces.

7. Identify four 7. Identify four instruments that are instruments that are used to measure relative used to measure relative humidity.humidity.

• Dew cellsDew cells

• PsychrometerPsychrometer

• Hair hygrometersHair hygrometers

• Polymer filmsPolymer films

8. Explain what would 8. Explain what would happen to a sample of happen to a sample of air whose relative air whose relative humidity is 100% if the humidity is 100% if the temperature decreased.temperature decreased.

• The rate of condensation would The rate of condensation would increase and dew or frost would increase and dew or frost would form.form.

The End…..The End…..

9. Which region of Earth 9. Which region of Earth would you expect to would you expect to have a higher absolute have a higher absolute humidity: the equatorial humidity: the equatorial region or the polar region or the polar regions.regions.

• Because it is warmer at the Because it is warmer at the equator and warmer air can hold equator and warmer air can hold more water vapor, the absolute more water vapor, the absolute humidity would be higher at the humidity would be higher at the equatorial region.equatorial region.

10. Use the following 10. Use the following terms to create a terms to create a concept map. concept map.

Humidity, water Humidity, water vapor, dew point, vapor, dew point, absolute humidity, absolute humidity, dew cell, dew cell, psychrometer, psychrometer, hygrometer, hygrometer, evaporation, evaporation, condensation, condensation, andand relative humidity.relative humidity.

Water vapor

Water vapor

humidity

Water vapor

humidity

Absolutehumidity

Relativehumidity

Water vapor

humidity

Absolutehumidity

Relativehumidity

Dew cell

psychrometer

hygrometer

Water vapor

humidity

Absolutehumidity

Relativehumidity

Dew cell condensation

hygrometer evaporation

psychrometer

Where would you put DEW POINT?

The EndThe End