Science Test- 4/26

Page 1

Air Masses, Fronts and Pressure Systems pgs 294-297

air mass

front- when two air masses meet

Air Masses

What is an air mass? A large volume of air in which temperature and moisture content are nearly the same throughout.

How do they form? An air mass forms when air over a large region stays in one area for many days. It can get stuck when there is no wind to push it other places.

Which is more dense, a cold or warm air mass? Cold- the molecules are closer so there are more of them in one mass

What is a cold front? Cold air comes under the warm air. It pushes the warm air up causing clouds to form and get bigger. Usually resulting in a storm.

What is a warm front? Warm air comes over cold air and pushes out the cold air. Usually results in overcast, drizzly weather.

Fronts

When do fronts form? When two air masses run into each other. Two air masses don't mix because of density differences. The front is the boundary between the two.

What things affect if a front is warm or cold? - How the masses move, their temperature, and moisture content

Pressure Systems

What are pressure systems?-

What is a high pressure system?

What is a low pressure system?- air comes together or converges and rises. As the air rises, it cools and forms clouds and rain.

Where is one place that a low pressure system typically forms? - Along the boundary between the warm air mass and a cool air mass?

How do pressure systems affect us?- If air stays in one place for too long, it takes on the temperature and humidity of the land. This can cause a pattern in the weather making it easier for scientists to predict the weather.

Page 2