1. Weather Fronts

2. cP air mass moves south The front of the cP air mass is obvious by the drastic difference in temperatures behind and in front of the air mass

3. A drastic difference in temperatures indicates a front

4. Locate the cold and warm front

5. 4 Types of Fronts 5

6. Fronts Boundary surfaces that separate air masses of different DENSITIES. one air mass is usually WARM and MOIST, the other one COLD and DRY vary in size: 15-200 km wide defined by their temperatures air masses move at different speeds and “clash” the warmer, less dense air always forced aloft (up) warm air overlies cold air and a slope is produced. form mid-latitude cyclones produce precipitation and severe weather.

7. Fronts Warm Front Symbol Speed Slope Clouds Precipitation Weather Winds Cold Front

8. Warm Fronts Warm air moves to occupy an area formerly covered by cooler air. Warm air masses: mT from Gulf of Mexico, or California, Mexico coast

9. Warm fronts Very gradual slope: 1:200km Speed: advance slowly 15 mph – 20 mph Clouds: cirrostratus, altostratus, nimbostratus Precipitation: light to moderate, over a wide area, long period of time. Weather: temps. gradually rise, fog, freezing rain Barometer: dropping below 30 in. Winds: from east to SW

11. Warm Front Unstable air mass

12. Warm Front Precipitation

13. Cold Front cP continental polar air (Canada) actively advances into an area formerly occupied by warm air.

14. Cold Fronts Slope: Twice as steep: 1:100 km Advance FAST: 20 mph-50 mph Clouds: altocumulus, then towering cumulonimbus Precipitation: heavy downpours, wind gusts over short duration Weather: violent weather, temperature drops, clear, fair weather after Barometer: rising (above 30 in.) Winds: shift from SW to NW

15. Cold Front

16. Thunderstorm Development along a Cold Front

17. Stationary Fronts Air flow is neither toward a cold air mass or a warm air mass Air flow is parallel to the front line The front does not move, or very slowly (after remaining over an area for several days) Precipitation is moderate, flooding possible.

18. Occluded Fronts Cold-Type Rapidly moving cold front, overtakes a warm front Cold air WEDGES the warm air upward Warm-Type Warmer air behind a cold front “catches-up” Ex; north Pacific Coast – warm mP invades the frigid cP air

19. Occluded Fronts Slope: Twice as steep: 1:100 km Advance fast: 20 mph-50 mph Clouds: altocumulus, then towering cumulonimbus Precipitation: heavy downpours, wind gusts over short duration Weather: violent weather, temperature drops, clear, fair weather after Barometer: rising Winds: shift from SW to NW

20. Occluded Front

21. 21

22. Front’s Bell work 1.Moves in the fastest _________ 2.Steady, light precipitation ___________ 3.Precedes cool, clear weather _________ 4.Has a slope of 1:200 km __________ 5.Does not advance forward or back for days ________ 6.Produces stratus clouds _________