Chapter 23 Section 1
Review Page 580
1. Explain how most water
vapor enters the air.
• When water molecules absorb heat
energy they move so rapidly they
escape the liquid and enter the air as
Water Vapor satellite image
2. Identify the principal
source from which most
water vapor enters the
• The oceans near the equator
3. Identify the process by
which ice changes directly
into a gas.
• Sublimation (have you ever seen dry
4. Define humidity.
• Humidity is water vapor in the
5. Compare relative
humidity with absolute
• Absolute humidity is the mass of water per
unit volume of air and represents a
measure of the actual amount of water in
the air (squeeze a wet sponge).
• Relative humidity is the ratio of water
vapor in the air compared to how much it
could hold at a given temperature (how
full is the sponge?).
6. Describe what happens when
the temperature of air
decreases to the dew point or
below the dew point.
• When temperature decreases the
rate of condensation increases, and
the rate of evaporation decreases. At
the dew point the rate of
condensation and evaporation are
equal. Below the dew point,
condensation occurs and visible
water droplets form on surfaces.
7. Identify four instruments
that are used to measure
• Dew cells
• Hair hygrometers
• Polymer films
8. Explain what would happen
to a sample of air whose
relative humidity is 100% if
the temperature decreased.
• The rate of condensation would
increase and dew or frost would
9. Which region of Earth
would you expect to have a
higher absolute humidity:
the equatorial region or the
• Because it is warmer at the equator
and warmer air can hold more water
vapor, the absolute humidity would
be higher at the equatorial region.
10. Use the following terms to
create a concept map.
Humidity, water vapor,
dew point, absolute
humidity, dew cell,
condensation, and relative
Dew cell condensation
Where would you put DEW POINT?