Homework Clinic
Science Clinic => Geography => Topic started by: meagbuch on Jul 13, 2018
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Explain the differences in air motion within a low pressure system and a high pressure system.
Question 2
List some of the ways in which you can predict the future movement of surface mid-latitude storms.
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Answer to Question 1
Horizontal pressure differences create a force that starts the air moving from higher pressure toward lower pressure. Because of the earth's rotation, the winds are deflected from their path toward the right in the Northern Hemisphere. This deflection causes the winds to blow clockwise and outward from the center of the highs, and counterclockwise and inward toward the center of the lows. As the surface air spins into the low, it flows together and is forced upward, like toothpaste squeezed out of an upward-pointing tube. The rising air cools, and the water vapor in the air condenses into clouds. In regions of high pressure, skies are generally clear. As the surface air flows outward away from the center of a high, air sinking from above must replace the laterally spreading surface air. Since sinking air does not usually produce clouds, we find generally clear skies and fair weather associated with the regions of high atmospheric pressure.
Answer to Question 2
For short time intervals, mid-latitude cyclonic storms and fronts tend to move in the same direction and at approximately the same speed as they did during the previous six hours (providing, of course, there is no evidence to indicate otherwise).
Low-pressure areas tend to move in a direction that parallels the isobars in the warm sector ahead of the cold front.
Lows tend to move toward the region of greatest surface pressure drop, whereas highs tend to move toward the region of greatest surface pressure rise.
Surface pressure systems tend to move in the same direction as the wind at the 500-mb level and at about half the speed.