Chapter 3; Section 1: Air Masses & Fronts
Terms in this set (9)
A hugh body of air that has the same temperature, humidity, and air pressure at any given height;
A single air mass may spread over millions of square km and be up to to 10 km deep.
Scientists classify air masses according to 2 characteristics
2. Humidity (moisture content of the region over which the air mass forms)
4 major types of air masses influence the weather in North America:
2. Continental tropical
3. Maritime polar
4, Continental polar
Temperature affects air pressure
1. Cold dense air has higher pressure
2. Warm less dense air has lower pressure
Tropical (warm) air pressures
form in the tropics and have low air pressures
Polar (cold) air masses
f1) form north of 50 degrees N latitude and south 50 degrees S latitude, and
2) have have high air pressure
Air mass may be humid or dry depending on whether it forms over water or land
1. Maritime air masses: form over oceans/ water evaoporates from oceans, so the air can become very humid
2)Continental air masses: form over land; have less exposure to large amounts of moisture from bodies of H2O.; ergo, are more drier than maritime air masses
1. Warm humid air masses form over tropical oceans.
2. Maritime tropical air masses that form over the Gulf of Mexico and the Atlantic Ocean move 1st toward SE US.
3. They then move N and NE, where they influence weather in the central and eastern US.
4. In the west, maritme tropical air masses form over the Pacific Ocean and mainly affect weather on the West Coast; as they cross the coastal mountain ranges, the Pacific air masses lose moisture.
5. In summer, maritime tropical aire masses usually bring hot, humid weather.
6. Many summer showers and thunderstorms in the eastern US develop in air masses that have formed over the Gulf of Mexico;
7. In winter, humid air mass can bring heavy rain or snow.
1. Cool, humid air masses from over icy cold N. Pacific and N. Atlantic oceans
2. Maritime polar air massesd affect the west Coast mor then the East Coast
3. Even in summer, these masses of cool, humid air often bring fog, rain,a nd cool temperatures to the West Coast