The document discusses different air masses that affect weather in North America. It describes how a maritime tropical air mass from the Pacific Ocean brings summer monsoon storms to the Sonora Desert region. It also explains that cold, dry air masses from the Canadian tundra region bring frigid winter conditions to parts of the United States. Additionally, it notes how air masses develop the temperature and moisture properties of their source regions and how these air masses can later modify local weather patterns as they move across landscapes.

1. Maritime Tropical Air Mass Brings Summer Storms over Sonora Desert

2. Canadian Tundra is Source Region for Cold Dry Air Masses

3. Cold, Dry Air
from Canada
Brings
Frigid Winter Air
to the United States

4. Air-Mass
Source Regions
for
North America

7. Air Masses Acquire the Temperature and Moisture Properties
of their Source Regions

8. Lake-Effect Snow Belts

9. Lake-Effect Snow

12. cP Air-Mass Modified As It Crosses the Ocean

13. Cumulus Clouds Developing when mT Air from the Gulf of Mexico
Moves over Heated Land in the Summer

14. Average Annual
Precipitation
in Eastern two-thirds
of the United States

15. Monthly Precipitation Data for Tucson, Arizona;
Summer Precipitation Results from Monsoon
Caused by mT Air Mass from the Pacific Ocean

16. Temperatures and Dew-Points at Weather Stations in the United States

17. Surface
Weather Map
during 1989
Cold Wave
Caused
by cA Air

18. Even Modern
Frost-Prevention Methods
May Not Be Able to Save
Florida Citrus Crops
during Cold Waves

19. A Record 69 Inches of Lake-Effect Snow Fell in Chardon, OH in 1996

20. Snow Totals
from 1996
Lake-Effect Storm