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Weather Patterns Chapter 15-2. I. Changes in Weather A. Air Masses 1. An air mass is … … a large body of air that has the same properties as the surface it develops over. 2. For example … a. Dry air mass over land Moist air mass over water
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I. Changes in Weather A. Air Masses 1. An air mass is … … a large body of air that has the same properties as the surface it develops over. 2. For example … a. Dry air mass over land Moist air mass over water b. Warm air mass over the tropics Cold air mass over the poles 3. Daily weather is due to … … movement of air masses.
B. Pressure Systems 1. Three things that determine atmospheric pressure are … -Temperature -Density -The amount of water vapor 2. High pressure is the result of … Descending (Sinking) Air 3. High pressure brings good weather because … Sinking air makes it difficult for air to rise and clouds to form.
C. Fronts 1. Low pressure systems form … … along the boundaries of air masses. 2. A Front is … … the boundary between two different air masses. 3. You would expect to see … storms and precipitation as a front passes overhead. 4. Air movement as fronts collide 5. The winds rotate counterclockwise as a result of … the coriolis effect.
D. Four types of fronts 1. Warm Front a. A Warm front occurs when … … less dense, warm air slides over a departing cold air mass. b. The precipitation associated with a warm front … … would be a wide band of precipitation. c. The clouds you would expected to see would be …cirrus.
2. Cold Front a. In a cold front … … a colder air mass pushes under a warm air mass and forces warm air up on a steep curve. b. A cold front produces … … a narrow band of violent storms. c. The type of clouds it produces would be … … cumulus and cumulonimbus.
3. Occluded Front a. An occluded front results from … … two cool air masses crashing together and forcing warm air between them to rise. b. You would expect to see … … strong winds and heavy precipitation.
4. Stationary Front a. A stationary front occurs when … … pressure differences cause warm and cold fronts to stop moving. b. In a stationary front you expect to see … … light winds and wide spread precipitation across the frontal region.