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Subject: Re: Physical Science -weather question

Author: Bridget

[ Next Thread | Previous Thread | Next Message | Previous Message ] Date Posted: 16:33:39 09/25/07 Tue In reply to: Kelly Hoffmann 's message, "Physical Science -weather question" on 12:58:52 09/24/07 Mon If you have a container of cold air and a container of warm air, the warm air will have greater pressure than the cold air. While talking about "Pressure Systems", the amount of air is so vast and can move that the concept is a little different. The high pressure systems contain air that is slowly coming down, warming as it does (they "fall" close to the earth). The air, as you say, does not rise, so it does have more pressure closest to the earth's surface. The low pressure systems have air that rises, and cools as it does so. While the air cools and rises, it is less able to hold water vapor. The water vapor comes out as rain, sleet, snow (depending on the surrounding temperature). The air has less pressure closest to the earth's surface because it is rising. I hope this helps. [ Next Thread | Previous Thread | Next Message | Previous Message ]