Sandra Dymott, age 12, of Winston‑Salem, N.C., for her question;
What is the monsoon?
It is spring, and the northeast monsoon sweeps down the Himalayas across India. It is a warm dry wind and the land, is parched. The streams and water holes are caked with mud. An old elephant leaves the herd and wanders down into the valley, hoping to slake his thirst at some forgotten pool. H;: finds nothing but the parched ground and the dry, oppressive wind.
Suddenly the wind changes, the skies cloud over and the rain pours down in torrents. The drenching summer monsoon has arrived from the, southeast. The valley streams are alive with gurgling water, the water holes full to the brim. Relief has come to countless thirsting animals and plants. To the old elephant it means tragedy. The dry ground is suddenly deep with mud. He cannot get out of the valley ‑ cannot even move. The changing of the monsoon wind is so sudden that many animals and even people are trapped by it every year.
The monsoon winds blow between vast areas of land and sea. Such winds blow from regions of warm air to regions of cooler air. And in monsoon areas, the vast masses of warm and cooler air change places with the seasons,
The air is warmed by the earth below it. Some air masses are warmed by the oceans and some by the: continents. The dry land gathers and loses its warmth faster than the sea. On a hot da;r, the land gets warmer than the sea. But at night it cools off faster. This explains the sea breezes, On a summer's day, a breeze blows from the cooler air over the sea towards the warmer air over the land. At night the wind reverses and blows from the land to the sea, which is now the; warmer of the two.
Monsoon winds follow the same principle as the sea breezes ‑ only on a giant scale. Instead of changing each day, they change with the season. All winter long, the. land masses are cooler than the oceans. The warm seas warm the air above. The cooler air over the cooler land masses must flow out towards the sea. It can gather no moisture as it blows over the land. Hence it is a dry wind and winter is a dry season.
Summer comes at last. The sun crosses the equator, the days become longer and warmer. The land masses drink up the sunshine become warm and then warm the air above them. For a few days the great masses of air over land and ocean almost balance. The: weather is heavy and oppressive. Then the balance suddenly shifts. The air masses over the land are now warmer than the air masses over the sea. The monsoon wind now blows from the opposite direction ‑ from the sea to the land.
The air masses over the sea are heavy with moisture all ready to deluge onto the parched land. This is the hot, wet, summer monsoon. It is the growing season for plants and crops. Heavy rains fall on and off throughout the season. Then the sun crosses the equator again. The sea holds on to its summer heat and the land cools off. Conditions are reversed again, After a short spell of uncomfortable fall weather, the monsoon wind turns about and blows from land to sea.