David Becheur, Age 10, Of Lancaster, Penna., for his question:

What causes a land breeze?

The land breeze and the sea breeze chase each other like a pair of playful puppies. Back and forth they blow across the shorelines of the ocean and the big lakes. In the tropics, a land and a sea breeze blow every clay, but in our temperate climate, they are summertime events. The land breeze carries the hot night air out to sea, and the sea breeze wafts cool air over the beaches during the day.

We go to the beaches to escape the scorching summer weather. There the day's and nights are cooler, arid for this we can thank the land breezes and the sea breezes. They are local winds that reach only a few miles inland and a few miles out to sea. The daily land and sea breezes are caused by the same weather conditions  so let's treat them like a pair of twins.

The face of the earth is warmed by sunbeams, and the air gets most of its warmth by touching the land and the sea. Warm air tends to expand and rise, and this makes pockets of thin, light air in the atmosphere. The cooler air around the thin patches tends to blow in to even the balance. Land breezes and sea breezes are just cooler drafts of heavier air flowing in to fill up thick pockets of thinner air.

The bum warms the earth in patches. On a summer day, the land gets warmer than a stretch of watery ocean. But after sunset, the land tends to lose its head in a hurry, while the water holds onto more of the warmth it gathered during the day.

In the daytime, the air over the land is hotter than the air over the sea. But at night the air over the land is cooler than the air over the sea. This turn about is caused by the land and the sea breezes that chase each other across the shorelines.

When the summer sun beats dawn, the air over the beaches becomes warm and light. It expands and rises. The cooler air over the sea flows inland, bringing a gentle sea breeze. The beaches are much cooler than they would be without this soft wind blowing from the sea.

After sunset, the air over the land is cool and heavy, and drafts of light, warmer air rise up from the ocean. Now the land breeze has its chance to blow. The cooler air over the beaches flows out to fill up the pocket. Of light air over the ocean.

The twin breezes reach less than a quarter mile above the earth, and above them the winds blow in opposite directions. The sea breeze starts to cool off the beaches about 10 in the morning, and it may reach 10 to 30 miles inland and another 10 to 30 miles out to sea. The land breeze begins an hour or so after sunset it starts about five miles and blows about five miles