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ATMOSPHERE
Lesson 3 - Page 6

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When the Sunís rays beat down on the land near a coastal area, the rays heat the air over the land quicker than the air over the oceans. Circulation is started when a "sea breeze" of cool air sweeps in from the ocean, pushing up the air warmed by the land which then rises (less dense) and streams out toward the ocean. Air cooled by the sea sinks and flows landward to fill the area of low pressure created by the warm land, causing onshore breezes. At night, the land loses its heat more rapidly than the water. The air above it is chilled, while the ocean air is relatively warm. The colder air now sweeps from the land to the water, producing the "land breeze."

This is best illustrated in the San Francisco area in California where you can see the wind blow the fog toward the hotter land. East of San Francisco the land gets very hot. The cold Pacific water is to the west. As the land heats up, the wind moves the fog quickly into San Francisco. It is very dramatic because there are coastal mountains that prevent the fog from going through most of the areas, so the fog rolls in through the Golden Gate bridge. Many people have never seen such a sight. 


Heating air to create wind


Fog moving into San Francisco Bay

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