1. Aim: What are air Masses?
Do Now: Take the worksheet from the Top Do Now Bin.
Read the passage. On the bottom of the sheet answer the question…
What is the jet stream and why is it weaker in the summer?

2. Do Now Answer:
Jet streams are fast moving currents of air in the upper troposphere. Like all winds, they form because of a difference in pressure.
They are weaker in the summer because the difference between high and low pressure in the summer is small. Since the difference in pressure is small, the winds are weaker.
This answer was found in the second paragraph. The article talks about the jet streams in the winter and you should be able to infer from this what happens in the summer.

3. I. Air Mass
- large parcel of air defined by moisture content and temperature.
- Source regions determine the characteristics of air masses.
Describe the temperature of air mass 1.
Describe the temperature of air mass 2.
Which air mass do you think is moist?

4. II. Characteristics of Air Masses
Page 13 ESRT
A) Moisture content: describes if the air is dry or moist. Indicated with a lowercase letter.
Maritime (m) source regions over water
- Continental (c) source regions over land

5. B) Temperature: describes if the air is warm or cool
B) Temperature: describes if the air is warm or cool. Indicated with an uppercase letter.
- Polar (P) source regions over high latitudes
- Tropical (T) source regions over low latitudes

6. Maritime Maritime Tropical Tropical mT mT
Using the notes you took, identify the air masses using the correct two letter symbols.
Continental 2
Polar
Maritime
Maritime cP 3
Polar 1
Polar mP mP
Continental
Polar 7 cP
Continental
Tropical 5
Maritime cT
Maritime
Tropical
Tropical 6 4 mT mT
Note: The arrows are pointing to where the air mass is moving, not it’s source region

7. III. Air Mass Movement
influenced by Jet Streams and prevailing winds.

8. “What are Air Masses?” Worksheet
Closure
Work on back of “Do Now”
“What are Air Masses?” Worksheet
After you complete the back of the sheet, take the second worksheet from the back bottom bin. Only work on the air masses side.