Activity 9: What Happens To Air When It Is Cooled? (WB pp 63-71)
Standards
Be able to: Form explanations based on accurate and logical analysis of
evidence. Revise the explanation using alternative descriptions, predictions,
models and knowledge from other sources as well as results of further
investigation.
The atmosphere has properties that can be observed, measured, and used to
predict changes in weather and to identify climatic patterns.
Introduction
This activity is related to the previous cloud’s activity in that it helps
students understand the conditions required for condensation to occur. It
develops the idea that the amount of water vapor in the air is related to the
dew point and air must be cooled to the dew point for condensation to occur.
Purpose
The purpose of this activity is to define and find the dew point temperature of
air in the classroom.
Part 1: Dew Point
Perform the dew point activity as directed by your teacher and record your data
below.
| Air Temperature | Dew Point Temperature | |
| Trial 1 | ||
| Trial 2 | ||
| Trial 3 | ||
| Average |
Answer the questions below.
1. Where did the water on the outside of the can come from?
__________________________________________________________
2. What do you think caused the air to condense?
__________________________________________________________
3. Why didn't the water vapor condense right away?
__________________________________________________________
4. Explain why the water formed on the outside of the
cup.
__________________________________________________________
5. What do you think might happen to the temperature of a mass of air as it
rises?
____________________________________________________________________________________
________________________________
6. What happens to water vapor as air rises and cools to the dew point?
_________________________________________________________
7. Suppose the water vapor did not condense until an even lower dew point was
reached. What would that tell you about the amount of water vapor in the air?
_____________________________________________________________
8. What would cause the dew point of a body of air to increase?
_____________________________________________________________