Air Masses & Fronts

What is an air mass? a giant bubble of air with the same temperature and humidity throughout Earth’s surface . . . . . . . .100’s of miles . . . . . . . . .

Air masses are named according to… ____________________________ known as their ____________ . the area over which they form source region

What is an air mass? a giant bubble of air with the same temperature and humidity throughout Earth’s surface . . . . . . . .100’s of miles . . . . . . . . .

Compare the air conditions in the Arizona Desert and the Florida coast. How would the temperature compare? Why? How would the humidity compare? Why?

Does the air mass form over… land or water? land = continental air mass (dry) ocean = maritime air mass (moist) a warm area or a cold one? warm area = tropical air mass (warm) cold area = polar air mass (cool)

There are four types of air masses: mT – maritime tropical – warm, moist air mP – maritime polar – cold, moist air cT – continental tropical – warm, dry air cP – continental polar – cool, dry air

Name the type of air mass that is shown at each of the following locations: 3 1 Location 1: mP Location 2: mT Location 3: cP Location 4: cT 4 5 2 Location 5: mT

How does a source region affect an air mass? Air masses get their characteristics from the location where they form, called their source region. How does a source region affect an air mass? The source region determines the temperature and humidity of the air mass.

Which two air masses affect Michigan the most?

cP mT

Why does the weather change so often in Michigan?

Two very different air masses meet right over our state! cP mT

Air Mass Review Air Mass Conditions Name an air mass!

Air Mass Review Air Mass Conditions cT warm, dry mT warm, moist mP cool, moist cP cool, dry Which air mass is the lightest? Which air mass is the heaviest? mT (least dense) cP (most dense)

the boundary between 2 different air masses What is a front? the boundary between 2 different air masses front warm, moist mT air cool, dry cP air Earth’ surface

How are fronts named? Fronts are named according to the type of air mass blowing into an area. If a warm air mass is blowing in, we call it a warm front. If a cold air mass is blowing in, we call it a cold front.

What type of front is shown here? W I N D front warm, moist mT air cool, dry cP air Earth’ surface Warm Front

Warm Fronts Warm fronts occur when warm, moist mT air blows over colder and more dense cP air. The warm air cools and the moisture condenses to form horizontal layers of clouds.

nimbostratus cloud mT air cP air

Warm Fronts = overcast skies Hours or days of gray, overcast (cloudy) skies On and off gentle rain (nimbostratus clouds) Pass slowly Bring warm, humid air NO SEVERE WEATHER!!!

What type of front is shown here? W I N D front cool, dry cP air warm, moist mT air Earth’ surface Cold Front

Cold Fronts Cold fronts occur when cooler, drier cP air scoops up the less dense mT air and forces it to rise straight up. The mT cools and the moisture condenses to form very tall cumulonimbus clouds .

mT air cumulonimbus cP air

Cold fronts produce cumulonimbus clouds, storms, and severe weather!

Cold Fronts = storms thunderstorms, lightning, and severe weather cumulonimbus clouds and heavy rainfall bring cooler, less humid air pass quickly hail, high winds, and/or tornadoes possible

After a cold front passes you can expect… Cooler temperatures Clearer skies Fair weather Drier air – lower humidity Higher pressure Rising barometer

Warm Fronts on a Weather Map cool, dry cP air warm, moist mT air In which direction is this front moving?

Warm Fronts

Cold Fronts on a Weather Map cool, dry cP air warm, moist mT air In which direction is this front moving?

A B Cold Fronts on the Weather Map What are the sky and temperature conditions like at city A? What are the sky and temperature conditions like at city B?

Main Types of Fronts: warm front – warm air blows in bringing overcast skies, gentle rain cold front – cold air blows in, overcast skies, thunderstorms, severe weather

Stationary Fronts

Resources http://www.uwsp.edu/geo/faculty/ritter/images/atmosphere/pressure_wind/low_pressure_small.jpg http://www.traveleye.com/northamerica/images/map.jpeg http://www.islandnet.com/~see/weather/graphics/photos/naairmass2.jpg http://members.aol.com/pakulda/images/stpptam.gif http://www.rvstogophx.com/images/arizona_desert_lg.jpg http://www.florida-gulf-villa.co.uk/Florida-beach.jpg http://recomb04.sdsc.edu/images/north_america.jpg http://www.ecn.ac.uk/Education/cold_fronts.htm http://www.atmosphere.mpg.de/media/archive/1822.gif www.photolib.noaa.gov http://ww2010.atmos.uiuc.edu/guides/mtr/af/frnts/wfrnt/gifs/def1.gif http://www.atmosphere.mpg.de/media/archive/1824.gif

http://www. newmediastudio http://www.newmediastudio.org/DataDiscovery/Hurr_ED_Center/Easterly_Waves/Geostrophic_Wind/Geostrophic_Wind_fig05.jpg

http://www2.cet.edu/weather/images/coldfront.gif