fronts, air masses, moving air changes weather

1. How Do Meteorologists Predict
Weather?

2. Air Masses and Fronts
What causes the weather to change?
•Air mass: a large
body of air that
has about the
same temperature
and humidity
throughout it
•Can be warm or
cold
•Can have a little
or a lot of
humidity

3. Air Masses and Fronts
• So large only 2
or 3 can cover
the U.S. at a
time
• Move west to
east
• Cold and warm
air masses stay
separate when
they meet
• The line where
air masses
meet is called a
front

4. What Happens When a Cold Air Mass
Pushes into a Warm Air Mass?
A Cold Front
Cold air, pushes warm
air upward quickly. Tall
storm clouds form and
may bring heavy rain ,
thunderstorms or in
winter, a snow storm.

5. What Happens When a Warm Air Mass
Catches up to a Cold Air Mass?
•A Warm Front
•The warm air
slowly rises over
the cold air
forming cirrus
clouds.
•These are
followed by lower
thicker clouds.
•A warm front may
cause rain or snow
for several days.

6. Tracking and Predicting Weather
• Keep track of
humidity, air
pressure, precipitati
on, air masses and
fronts
• Speed and direction
of wind help predict
where air masses
will move

7. Study Jams Air Masses and Fronts