air masses & fronts. what is an air mass? an air mass is a huge body of air that influences...
TRANSCRIPT
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
TROPICAL
MARITIME
POLAR
CONTINENTAL
TROPICAL
CONTINENTAL
POLAR
North American Air Masses
MARITIME POLAR
CONTINENTAL POLAR
MARITIME POLAR
MARITIME TROPICAL
MARITIME TROPICAL
CONTINENTAL TROPICAL
How do these air masses move?
MARITIME POLAR
CONTINENTAL POLAR
MARITIME POLAR
MARITIME TROPICAL
MARITIME TROPICAL
CONTINENTAL TROPICAL
Jet Stream Jet Stream
Prevailing Westerlies
That’s why weather generally moves WEST to EAST
in the U.S.
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 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
Stationary Front
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
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
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)
Stationary Front
Occluded FrontWarm Front
Cold Front
HHHigh Pressure
LLLow Pressure
Precipitation
Temperature Map
Stationary Front
Occluded FrontWarm Front
Cold Front
HHHigh Pressure
LLLow Pressure
30°C
14°C
15°C
12°C
28°C 21°C
20°C
26°C
25°C
19°C
Monday WeatherLittle Rock, AR
Sun & clear skiesCool = 15°C
Tuesday WeatherLittle Rock, AR
Clouds & RainWarmer = 21°C
Wednesday WeatherLittle Rock, AR
Partly SunnyWarmer = 26°C
Which direction is the warm front moving?
What will happen to the weather in Little Rock?
Stationary Front
Occluded FrontWarm Front
Cold Front
HHHigh Pressure
LLLow Pressure
18°C
10°C8°C
20°C
Thursday WeatherNashville, TN
Partly SunnyWarm = 20°C
15°C
11°C
10°C
10°C
Which direction is the cold front moving?
What will happen to the weather in Nashville?
Friday WeatherNashville, TN
ThunderstormsCooler = 15°C
Saturday WeatherNashville, TN
SunnyCool = 10°C