Mrs. Downs' Science Classes – Fronts & Storms – Chapters 29

Fronts & Storms – Chapters 29 – 30 Notes & Review Questions

Directions: First read Chapters 29 – 30 in your Earth Science textbook.

When a mass of air sits in one area for a while, it takes on the temperature and humidity of that area. Then if it begins to move across the Earth, it takes that temperature and humidity with it. There are four main types of air masses that affect weather in the U.S.A.:

	maritime tropical (abbreviated mT) forms over the ocean in the tropics, like over the Gulf of Mexico, so the air is warm and moist.
	maritime polar (mP) like a mass that forms over the Arctic Ocean, is cold and moist air.
	continental tropical (cT) like a mass that forms over Mexico, is hot and dry.
	continental polar (cP) like a mass that forms over Canada, is cold and dry.

There is also a continental arctic (cA) that is extremely cold and dry, but those air masses seldom get as far south as the U.S.

Fronts form as air masses begin to move, pushing other air masses in front of them. There are four main types and the weather they bring varies greatly.

A cold front occurs when a cold air mass is pushing a warm one. The cold air mass is denser, so it bulldozes its way underneath the warm air mass, lifting it as it moves across the land. The angle of the front is steep, so “vertical development” occurs in the clouds along the front. The front moves quickly, so you end up with short, violent thunderstorms. The symbol for a cold front on a weather map is:

A warm front occurs when a warm air mass is pushing a cold one, usually riding up over it as it pushes it along. The front moves slowly, so you end up with a long, slow, steady rain. The symbol for a warm front on a weather map is:

If the air masses stop moving, a stationary front occurs. If this lasts for any length of time, the boundary breaks down and the air masses mix, and the “front” disappears. The symbol for a stationary front on a weather map is:

If a fast moving cold front “catches up” with a slow moving warm front, the warm mass is lifted aloft and an occluded front occurs. The symbol for an occluded front on a weather map is:

Let’s just skip the Focus Questions and Vocabulary again (in the interest of time) and go straight to the Review Questions:

	Pages 554 – 555, do the 17 Review Questions and the 4 Critical Thinking Questions.
	Pages 572 – 573, do the 20 Review Questions and the 5 Critical Thinking Questions.