Sea Breeze
The difference in temperature between land and sea surfaces produced by the same radiation intensity leads to a circulation
system known as land and sea breeze. Both land and sea breezes are examples of strongly forced circulations which either
modify the large scale winds, or, in the case of large scale calm conditions, cause winds to blow across shore lines of the
ocean, lakes and large rivers. The Coriolis force usually turns the winds so that the direction is nearly parallel to the shore.
The sea breeze can be demonstrated by using two cans of 3" diameter, such as pet food cans, and 1" height filled with fine
dry dark soil and the other with water placed inside an box. The soil should be sifted and should be as dark as possible to
increase the absorbency of light. If only light soil is available, darken it by mixing soot, copier toner or charcoal powder
into it.
The box should be constructed so that the top and front are transparent but the other walls are either painted flat black or
lined with construction paper.
Place
both cans in an aquarium or a box with transparent top and front as in the diagram.
For better visibility of the smoke used in the experiment, the inside of the
back and side panels should be painted flat-black or lined with black construction
paper. Then fasten, with cement or tape, a sheet of glass or plastic to the
top; a transparent plastic sheet is taped to the front, so that it can be removed
for setting the two tin pans inside or taking them out. Cut a small hole in
the front plastic just above the base to insert some smoke.
Place a 150 or 200 watt light bulb about 4" above the middle of the
top, so that the same radiation is received by each of the pans. The
bulb is turned on, and after 15 to 20 minutes very slowly blow some
smoke through the hole in the front panel being careful not to create
any eddies. The smoke should merely seep into the box. Watch the
smoke drift and describe the motion.
Material: Two tin cans of 3" diameter
One box with top and front removed
Some flat-black point
Transparent plastic to cover front and top
Some dark, sifted soil; water
A smoke source
A 150 or 200 watt light bulb.