Download Air Masses & Fronts

Essential Question:
How does heating affect the
movement of molecules in the
atmosphere?
Learning Target
I can discern the effects of global
winds, and the jet stream on
weather and climatic conditions.
Air Masses
& Fronts
What is an AIR MASS?
• An air mass is a huge body of air that
influences weather.
• Scientists classify air masses based on:
TEMPERATURE
and
HUMIDITY
Air Masses are named based on where
they FORMED…
= TROPICAL
= POLAR
= MARITIME
(means sea… wet)
= CONTINENTAL
(means land… dry)
How are Air Masses named?
MARITIME
CONTINENTAL
TROPICAL
TROPICAL
MARITIME
CONTINENTAL
POLAR
POLAR
North American Air Masses
MARITIME
POLAR
MARITIME
TROPICAL
CONTINENTAL
POLAR
CONTINENTAL
TROPICAL
MARITIME
POLAR
MARITIME
TROPICAL
How do these air masses move?
MARITIME
POLAR
CONTINENTAL
POLAR
MARITIME
POLAR
Jet StreamThat’s why weather
generally moves
WEST to EAST
in the U.S.Westerlies
Prevailing
MARITIME
TROPICAL
CONTINENTAL
TROPICAL
MARITIME
TROPICAL
What happens when air masses
meet?
• Air masses don’t mix easily.
• The line between air masses is called a
front.
COLD FRONTS
WARM FRONTS
Watch the BrainPop
video on “Weather”
and write down 2
things you learned.
Use your textbook (pg.133-135) to fill out the chart.
Compare/Contrast Chart - Types of Fronts
Front
Cold
Front
Warm Front
Stationary Front
Occluded Front
How it Forms
A fast-moving cold air
mass overtakes a warm
air mass.
Type of Weather
Clouds form.
If warm air is humid,
rain/snow may fall.
Possible thunderstorms.
Compare/Contrast Chart - Types of Fronts
Front
Cold
Front
Warm Front
Stationary Front
Occluded Front
How it Forms
A fast-moving cold air mass
overtakes a warm air mass.
Type of Weather
Clouds form.
If warm air is humid,
rain/snow may fall.
Possible thunderstorms.
A warm air mass
Scattered clouds.
overtakes a slow-moving Light rain or snow.
cold air mass.
May last several days.
Compare/Contrast Chart - Types of Fronts
Front
How it Forms
Type of Weather
Cold
Front
A fast-moving cold air mass
overtakes a warm air mass.
Clouds form.
If warm air is humid,
rain/snow may fall.
Possible thunderstorms.
Warm Front
A warm air mass overtakes
a slow-moving cold air
mass.
Scattered clouds.
Light rain or snow.
May last several days.
Stationary Front Cold and warm air meet, Rain, snow, clouds, or
but neither can move the fog that may last for
other. Creates “standoff” days.
Occluded Front
Compare/Contrast Chart - Types of Fronts
Front
How it Forms
Type of Weather
Cold
Front
A fast-moving cold air mass
overtakes a warm air mass.
Clouds form.
If warm air is humid,
rain/snow may fall.
Possible thunderstorms.
Warm Front
A warm air mass overtakes
a slow-moving cold air
mass.
Scattered clouds.
Light rain or snow.
May last several days.
Stationary Front
Cold and warm air meet,
but neither can move the
other. Creates “standoff”
Rain, snow, clouds, or fog
that may last for days.
Occluded Front
A warm air mass is
caught between 2 cooler
air masses. Warm air
mass is pushed up.
Temperature gets
cooler.
Clouds and rain may
form.
Surface Map (Fronts & Precipitation)
Precipitation
High Pressure
Low Pressure
H
L
Warm
Front
Occluded Front
Cold Front
Stationary Front
Temperature Map
Which
Whatdirection
will happen
is the
to warm
the
weather
frontinmoving?
Little Rock?
12°C
19°C
14°C
20°C
25°C
Wednesday
Tuesday
Monday Weather
Weather
Little Rock, AR
28°C
15°C
21°C
26°C
30°C
High Pressure
Low Pressure
H
L
Sun
Clouds
Partly
& clear
Sunny
& Rain
skies
Warmer
Cool = =15°C
21°C
26°C
Warm
Front
Occluded Front
Cold Front
Stationary Front
What
Which
will
direction
happenis
tothe
the
weather
cold front
in Nashville?
moving?
10°C
8°C
18°C
11°C
10°C
Thursday
Saturday
Friday Weather
Weather
Weather
Nashville, TN
15°C
10°C
20°C
Thunderstorms
Partly
Sunny
Sunny
Cooler
Warm
Cool ===10°C
20°C
15°C
High Pressure
Low Pressure
H
L
Warm
Front
Occluded Front
Cold Front
Stationary Front