Download air_masses_and_fronts - Red Hook Central Schools

Weather Instruments
These are the instruments that measure the primary
Barometer
weather variables in our atmosphere
Rain gauge
Thermometer
Anemometer
Sling psychrometer
Most sudden changes in the weather are
a result of Air Masses
An air mass is defined as:
a large parcel of air
that has taken on the characteristics of the surface
over which it has been sitting
When an air mass sits over a surface of the earth
It can acquire 2 primary properties
1. temperature
2. moisture content
How many possible combinations of air masses could
you have using only these 2 variables?
1.warm and moist
2. warm and dry
3. cold and moist
4. cold and dry
What type of surface would these air masses form over?
Cold air mass
cP
mT
cT
The leading edge of an air mass is called a
FRONT
The symbols point
in the direction the
air is moving
COLD FRONT
COLD air mass advances on a WARM air
mass, pushing forward into the warm air
WARM FRONT
WARM air mass advances on a COLD air
mass.
Since the cold air is more dense, the warm
air mass is forced to rise as it pushes
forward
OCCLUDED FRONT
TWO cold fronts approaching each other are
separated by a warm air mass
As the two cold fronts near each other, the
warm front is pushed up over the cold front
and off the ground
Stationary Front
A warm air mass and a cold air mass are
adjacent to each other, but do not move
The leading edge of an air mass is called a:
Front
Here is a surface map showing a cold front
that has just moved through the midwest
The following things usually
cold front side view
happen as a cold front approaches
and moves past a location:
1. A rapid increase in cloud cover, usually tall cumulous or
cumulonimbus type
2. A rise in the wind velocity, and shift in direction from
south to north
3. Brief heavy precipitation or thunderstorm possible
4. A rapid fall in pressure, followed by a gradual rise
5. A sharp drop in temperature
Notice the high angled slope
or pitch
Simulation at high speed
Warm front side view
1. A steady drop in pressure
3. A gradual increase in clouds
until entire sky is covered
The following weather changes
usually occur as a warm front
approaches
2. Cirrus clouds are first indication
of approaching warm front
4. A gradual increase in temperature
6. A shift in the winds from
north to south
5. Long term light to moderate
precipitation
A warm front is a much
gentler slope or pitch
Changes in the weather
Occur much more slowly