BACKGROUND:
Land and water retain heat
differently. Water retains heat much longer than land, although it
takes a longer time to heat up. Land cools and heats up more quickly
than water. Day and night causes a large change on land, but not
in water. The larger a body of water is the longer it takes to heat
and cool.
The Sun beating down on the coastal
land heats the land and the air over it more quickly than it heats the
ocean and its overlying air. 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 breeze. 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."
Winds are also created when warm
air rises and cool air falls. When you hear the terms cold front
or warm fronts they are generally talking about a mass of air with the
same temperature. A front is when two masses of air meet. When
2 different masses of different temperature meet, it creates a different
type of weather.
The San Francisco area in California
is famous for its fog. Many people in the area do not even realize
why the fog comes into town. The story has to do with sea breezes.
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
PROCEDURE:
- Give students
a worksheet and go over each of the diagrams. You may want them to
color the water blue, so it stands out better. The answer to the
question is on the diagram. Make sure students notice the difference
of temperature, which is the driving force behind the sea and land breezes.
- You may want students to
discuss the difference of living near a coast and living inland.
