AIR MASSES AND FRONTS Chapter 16 Section 2 1. A front is a boundary between air masses. Four types of fronts and map symbols 1.Cold front 2.Warm front.

AIR MASSES AND AIR MASSES AND FRONTSFRONTS

AIR MASSES AND AIR MASSES AND FRONTSFRONTS

Chapter 16 Section 2Chapter 16 Section 2

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• A front is a boundary between air masses.

• Four types of fronts and map symbols

1. Cold front2. Warm front3. Occluded front4. Stationary front

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WARM FRONT

• Warm air mass meets a cold air mass and pushes the cold air mass out of the way.

• Brings drizzly precipitation.

• Followed by clear warm weather.

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A warm front occurs when a less dense air mass rides up over a more dense air mass.

Symbol:

• Warm Front Animation:– http://ww2010.atmos.uiuc.edu/(Gl)/guides/crclm/act/gifs/fp

r4.gif– http://earthsci.org/processes/weather/weaimages/2e.gif

Clouds, Storms, and rain accompany warm fronts.

Moving warm air mass collides with a slowly moving cold air mass

COLD FRONT

• Cold air mass meets a warm air mass and pushes the warm air mass out of its way.

• Bring thunderstorms, rain or snow.

• Most tornadoes develop from • thunderstorms on the edge of a cold front.

• Cold front followed by cooler drier air.

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A cold front occurs when a more dense air mass pushes under a less dense air mass.

Symbol:

Cold Fronts can cause heavy snow or ice if there is enough water vapor in the air.

STATIONARY FRONT

• Cold air meets warm air.

• Not enough force to move either front.

• Many days of cloudy, wet weather.

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• Warm air mass and cold air mass meet

• Neither has enough force to move the other so they just stay in the same place.

• Where they meet, water vapor in the warm air condenses into rain, snow, fog or clouds

• Can stall out for days

Symbol:

Stationary Fronts:

• Stationary Front Animation:– http://www.usatoday.com/weather/tg/wsfront/wsfront.htm

Unlike a fast-moving front, Stationary fronts often bring several days of cloudy, wet weather that can last a week or more.

OCCLUDED FRONT

• Warm air caught between two cold air masses.

• Brings cool temperatures with large amounts of rain or snow

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• http://www.uwsp.edu/geo/faculty/ritter/images/atmosphere/weather/cold_occlusion.gif

Occcluded Fronts:The two cooler air masses meet in the middle and may mix.

The warm air mass is cut off (or occluded) from the ground.

A warm air mass is caught between two cooler air masses

Symbol:

Cold Front, Warm Front and Occluded Front Animation

• http://www.3villagecsd.k12.ny.us/Murphy/medina/weather.html

• http://www.classzone.com/books/earth_science/terc/content/visualizations/es2002/es2002page01.cfm?chapter_no=visualization

• Click on the above links.

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Humidity• the amount of water vapor in the

air

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An air mass is an extremely large body of air whose properties of temperature, moisture content (humidity) and air pressure are similar throughout . Air masses can cover hundreds of thousands of square miles.

• Warm air forms over tropical regions near the equator. T- Tropical

• Cold air forms over polar regions. P- Polar

• Wet air masses form over water m- maritimeDry air masses from over land. c- continental

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• Moisture content is noted by the first letter.

m – maritime – wetc – continental – dry• Temperature is noted by the second

letter.P – polar – coolT – tropical - warm

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Description of air masses:– Continental polar (cP)- cold and dry-

forms over land, High Pressure– Continental tropical (cT)- warm (hot)

and dry- forms over land (Low Pressure)

– Maritime polar (mP)- Cold and Humid (wet); Forms over cold water (High Pressure)

– Maritime tropical (mT)- Warm and humid(wet); Forms over warm water (Low Pressure) 19

• mP- maritime polar air mass

• cP – continental polar air mass

• mT – maritime tropical air mass

• cT – continental polar air mass

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An air mass is a large body of air that has similar temperature and moisture properties

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