Download Air Masses and Weather Fronts

Air Masses and
Weather Fronts
Air masses
•
•
A body of air with
similar
characteristics
throughout
Humidity and
temperature are
the two main
characteristics
used to classify
air masses.
The “first name” of an air mass
describes the humidity of the air mass.
• Maritime
– humid (wet) air
masses that form
over oceans
• Continental
– drier air masses
that form over land
The “last name” of the air mass
describes the temperature of the air
mass.
• Polar
- cold air masses out
of the north
• Tropical
- warmer air masses
from the south
e.g. A Maritime tropical air mass
forms over warm ocean water,
making the air
__________
moist and __________
warm
What causes the movement of these
air masses?
• Prevailing westerly winds push maritime polar
air masses from the Pacific onto the west coast,
but push maritime polar air masses out to sea on
the east coast.
Fronts
• The area where two air masses meet and
don’t mix is called a front. In other words
a front is the boundary between two or
more air masses.
There are 4 types of fronts
• Cold Front – Fast moving cold air runs into a
slow moving warmer air mass; the cooler air
slides under the warmer air and pushes the
warmer air upward.
• Warm Front – Warm air mass collides with a
slow moving cold air mass; warm air is less
dense and so moves over the cooler air
• Stationary Front – Cold and
Warm air masses meet,
without either air mass being
moved by the other.
• Occluded Front – A warm air
mass is caught between two
cooler air masses and is lifted
above them.