FRONT AND CENTER!
Objective
You will be able to identify characteristics of the formation of a cold front, warm front,
stationary and an occluded front in order to describe the weather patterns associated with each
type of front.
Activity 1:
1.
Front- ___________________________________________________________________
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2.
3.
What are the types of air masses that interact to form weather fronts?
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Predict how fronts are similar. (Use details from the visuals you observed to help you form
your prediction.)
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Activity 2:
4.
Read the attached reading.
5.
Complete Chart 1, Frontal Systems
Activity 3:
6.
Using the information from your notes to label each picture with the type of front
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7.
Create your own drawing for the two remaining fronts.
Include:

Temperature of air (warm or cool)

Arrows showing direction of moving

Where rain will occur
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Analysis
“I hope you’re sitting down folks, because our weather computer’s gone
haywire! It’s showing us that the earlier prediction was wrong. Apparently the
forecasts can change as quickly as the weather. The National Weather Service
is now issuing a severe thunderstorm warning for our entire viewing area!
Better take cover quickly. The sky is falling! Once the storm passes we will
have a cool, clear rest of the day. ”
Identify and describe the frontal system associated with the weather described in the
weather report. Support your choice using a quote from the above description.
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“”O.K. boys and girls get your rain boots on because we are in for long couple
of days. We have a continental tropical air mass running into a continental
polar air mass and neither of them will give. If one of these air masses doesn’t
budge we will be in for a long couple of day’s of rain and even some fog may
cover the immediate area! ”
Identify and describe the frontal system associated with the weather described in the
weather report. Support your choice using a quote from the above description.
___________________- _____________________________________________________
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Chart 1
Frontal Systems
FRONTAL SYSTEM
Cold Front
Warm Front
Stationary Front
Occluded Front
HOW IT FORMS
HOW IT AFFECTS THE WEATHER
After the front passes
Types of Fronts
What are Fronts?
As huge masses of air move across the land and the oceans, they collide with each other. When
the air masses run into each other they do not easily mix. Think about a bottle of oil and water. The less
dense oil floats on top of the denser water. Something similar happens when two air masses with a
different temperature and humidity collide. The air masses do not easily mix. The boundary where the
air masses meet becomes a FRONT. Storms and changeable weather often develop along the fronts.
The colliding air masses can form four types of fronts: cold fronts, warm fronts, stationary fronts, and
occluded fronts.
Cold Fronts
As you have learned, cold air is dense and tends to sink. Warm air is less dense and tends to rise.
When a rapidly moving cold air mass runs into a slowly moving warm air mass, the denser cold air
slides under the lighter warm air. The warm air is pushed upwards along the leading edge of the colder
air and a cold front is formed.
Once the warm, moist, less dense air is forced up into the upper atmosphere it cools creating
clouds. If there is a lot of moisture in the air, heavy rain or snow may fall. Because the front moves
quickly, abrupt weather occurs and thunderstorms can form.
After the front moves through it brings clear skies and cooler temperatures.
Warm Fronts
At a warm front, a fast moving warm air mass overtakes a slowly moving cold air mass. Because
cold air is more dense than warm air, the warm air moves above the cold air. The warm air is pushed up
over top the leading edge of the colder air and a warm front is formed.
Once the warm air is pushed up, if the air is humid, light rain or snow will fall along the front. If
the warm air is dry the area will just have heavy cloud cover for multiple days.
Warm fronts move slowly so an area will receive precipitation or clouds for several days. After a
warm front passes through an area, the weather is likely to be warmer and humid.
Stationary Fronts
Sometimes cold and warm air masses collide, but neither one can move the other. The two air
masses face each other in a “standoff”. This is called a stationary front.
Where the warm and cool air meet, the water in the air condenses into rain, snow, fog or just a
cloudy day will ensue.
It is possible for a stationary front to stick around for a few days. The weather that follows will
depend on which air mass wins the battle and moves in over the area.
Occluded Fronts
This is most complex weather situation. An occluded front occurs when two fronts run in to each
other. The warm air between trapped between two cooler air masses. The denser cool air masses move
underneath the less dense warm air mass and push the warm air upward. The two cool air masses meet
in the middle and mix.
The difference between the temperatures of the air masses means that this front usually does not
last for very long. The occluded fronts stick around for only a short period of time and the weather may
turn cloudy and a chance of precipitation my form.
After the front moves through, the weather will become cooler with cloudy skies.
Warm air and cool air run
into each other forcing
the warm air to rise into
the atmosphere quickly
-
-Fast moving warm air
mass moves overtop a
slow moving cold air mass
forcing the warm air to
rise into the upper
atmosphere
-A warm and a cold air
mass collide but neither
air mass rises
-Two fronts run into each
other
Warm air is trapped
between two cold air
masses and is forced up
quickly
-Cool air masses mix
-Heavy rain or snow
-Thunderstorms may form
------------Humid air –light rain or
snow
-Not humid- cloudy for a
few days
-Rain
-snow
-fog or
-cloudy for multiple days
-Cloudy
-chance of precipitation
Clear and cool skies
Warmer and humid skies
Depends on which air mass
winds
Cooler with cloudy skies