Chapter 25 Weather

1. Chapter 25Weather Section 2 Fronts Notes 25-2

2. Fronts • When two unlike air masses meet, density keeps them separate • Warm air is less dense than cold air • Front is made between the two air masses • Changes in the middle latitude weather takes place along fronts • Can be from 100’s of km long to 1000’s of km long • There are no fronts in the tropics • Air is all the same

3. Types of Fronts • Cold front: cold air over takes warm air • Warm air is lifted by cold air • Warm, moist air will form clouds • Fast moving cold front • Large cumulus or cumulonimbus clouds • Storms are short and violent • Squall line: long line of heavy thunderstorms • Will form ahead of front

4. Types of Fronts • Cold Front: • Slow moving front • Lifts the air slower • Produces less cloudiness and lighter precipitation

5. Fast Moving Cold Front

6. Types of Fronts • Warm Front: • Warm air overtakes a cooler air mass • Warm air rises over cool air • Slope is gradual • Clouds may extend far ahead of the base of the front

7. Types of Fronts • Warm Front: • Types of clouds • Cirrus clouds = beginning of front • Cirrostratus clouds = next • Altostratus clouds = next • Low stratus clouds = next • Nimbostratus clouds = at base of front • Produces precip. over a large area • Could be violent if the warm air is very moist

8. Warm Front

9. Types of Fronts • Stationary Front: • Front that does not move • When two air masses meet and neither can be displaced • Air masses move parallel to each other • Weather is similar to a warm front

10. Types of Fronts • Occluded Front: • Fast moving cold front overtakes a warm front • Lifts warm off the ground • Cold front comes up to the cold air replacing the warm that just went up into the sky • Warm air becomes secluded above the cold air

11. Occluded Front

12. Types of Front Symbols