1. AIR MASSES AND FRONTS Chapter 16 Section 2 1

2. A front is a boundary between air masses. Four types of fronts and map symbols 1.Cold front 2.Warm front 3.Occluded front 4.Stationary front 2

3. 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. 3

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

5. Warm Front Animation: –http://ww2010.atmos.uiuc.edu/(Gl)/guides/crclm/act/gifs/fpr 4.gifhttp://ww2010.atmos.uiuc.edu/(Gl)/guides/crclm/act/gifs/fpr 4.gif –http://earthsci.org/processes/weather/weaimages/2e.gifhttp://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

6. 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. 6

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

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

9. STATIONARY FRONT Cold air meets warm air. Not enough force to move either front. Many days of cloudy, wet weather. 9

10. 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:

11. Stationary Fronts: Stationary Front Animation: –http://www.usatoday.com/weather/tg/wsfront/wsfront.htmhttp://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.

12. OCCLUDED FRONT Warm air caught between two cold air masses. Brings cool temperatures with large amounts of rain or snow 12

13. http://www.uwsp.edu/geo/f aculty/ritter/images/atmos phere/weather/cold_occlus ion.gifhttp://www.uwsp.edu/geo/f aculty/ritter/images/atmos phere/weather/cold_occlus ion.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.

14. A warm air mass is caught between two cooler air masses Symbol:

15. Cold Front, Warm Front and Occluded Front Animation http://www.3villagecsd.k12.ny.us/Murphy/me dina/weather.htmlhttp://www.3villagecsd.k12.ny.us/Murphy/me dina/weather.html http://www.classzone.com/books/earth_scien ce/terc/content/visualizations/es2002/es2002 page01.cfm?chapter_no=visualizationhttp://www.classzone.com/books/earth_scien ce/terc/content/visualizations/es2002/es2002 page01.cfm?chapter_no=visualization Click on the above links. 15

16. Humidity the amount of water vapor in the air 16

17. 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- maritime Dry air masses from over land. c- continental 17

18. Moisture content is noted by the first letter. m – maritime – wet c – continental – dry Temperature is noted by the second letter. P – polar – cool T – tropical - warm 18

19. 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

20. mP- maritime polar air mass cP – continental polar air mass mT – maritime tropical air mass cT – continental polar air mass 20

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

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