ch 8 weather systems GEOG 2050

ch 8 weather systems GEOG 2050 - Weather Systems We know...

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Weather Systems We know that rising air cools at DALR/SALR Air mass: large region of air with uniform temperature and humidity Fronts: boundary between 2 air masses Types of air masses: Temperature: o Very cold – Arctic (A) o Cool – Polar (P) o Warm – Tropical (T) Moisture: o Wet – Maritime (m) o Dry – Continental (c) All of these can be combined to form the five types of air masses: o mP, mT, cA, cP, cT o We usually don’t get arctic air masses that are very humid that is why mA does not exist. Source regions: typical foundation areas – masses that form over the oceans tend to have more moisture than masses that form over land o Example is the subtropical highs and subpolar low As they move they acquire surface characteristics. They also force away whatever air mass was in their way. Fronts: boundary between air masses and is the leading edge of the temperature and humidity change. Fronts are named based on the air mass behind it. Types of fronts: o Cold – (blue triangles) advancing cold air rapidly and strongly pushes warm air upward. As the cold air moves in it digs under the warm air and pushes it upward. This is a great location for clouds, precipitation, and possibly severe weather. Precipitation is usually heavy but brief. o Warm – (red semi-circles) advancing warm air. The warm air gently rises over the cold air mass, which is not as strong as the cold front. Results in light and steady rainfall. Clouds take up more space and have more aerial cover Overrunning: process of warm air gently rising over a cold air mass. This also causes inversions – freezing rain happens in the wintertime during a warm front. o Stationary – (alternating blue triangles and read semi-circles) the boundary where there is a cold air mass and a warm air mass but they are not going into each other. They are either running parallel to each other or they are not moving at all. There will always be large temperature differences on either side of the front. This results in some precipitation and clouds and looks like a warm front. Zone of transition – more gradual transition than a cold front o Occluded – (purple) two cold air masses “close off” the warm air mass in between them. It happens when there is a very large low-pressure system. The cold front “catches” the warm front. Final Exam
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Weather Systems o Dry Line – (red hash mark) usually in the south central US. Not really associated with air masses. Stationary conditions but there are no temperature differences but big moisture differences. A boundary between two air masses with similar temperature but different humidities. This is a good place to get thunderstorms in the spring and summertime – this is the reason for severe weather in the mid west. Stages of Mid-Latitude Cyclones
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This note was uploaded on 10/11/2011 for the course PSYC, PSYC 2076, 2060 taught by Professor Briganti,gustan,perlis,namikas,wheeler during the Spring '10 term at LSU.

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ch 8 weather systems GEOG 2050 - Weather Systems We know...

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