In our Library - where Books are free

Books - Factual

Sociology

Poverty - by James Platt

All wind is caused directly or indirectly by a change of temperature. Suppose the temperature of two adjoining regions to become different, one hotter and the other colder; the air of the warmer will become lighter and ascend, the cold air being heavier, will flow in to take its place. Stand upon a pair of steps, and ascend until your head is near the ceiling, and you will find it very warm, the gas or lamp making it so. Open the door of a warm room, and you feel the rush of the cold air. "That is wind."

There are "constant winds," and from the benefits they confer upon our merchants are called " trade winds." When a part of the earth's surface is a whole zone or division of the earth, as in the tropics, a surface wind will set in towards the heated tropical zone from both sides, and uniting, will ascend, and then separating, will flow as an upper current in opposite directions. Hence a surface current will flow from time higher latitudes towards the equator, and an upper current towards the poles. If then, the earth were at rest, and not moving at all, we should have