Daniel Argurieo, age 9, of st. Louis, Mo., for his question:
Where do the trade winds blow?
Most of the winds that blow over St. Louis Come from the West. These world wide Westerly winds circle around the globe. The trade winds blow from the east and circle the globe nearer the equator. You could find them south of St. Louis, for they blow across Florida and the Gulf of Mexico.
The winds blow this way and that as they choose but most of the time big winds blow in orderly paths like wide belts around the earth. And they blow more or less from the east to the west. Most of us live in the Westerly wind belt where steady winds carry our changing weather across the land from the southwest. Farther south, the trade winds blow eastward around the globe, and in the far north the polar winds also blow from the east.
Little local winds and breezes blow this way and that, but the big circling winds prevail most of the time. We call them the prevailing winds or planetary winds because they sweep is set paths around our planet. You can trace their paths by finding the lines of latitude that circle around a globe or on a map of the world.
The equator runs around the wide waist of the world. It is latitude 0 degrees north of the equator there are circles of latitude that become smaller and smaller as they come closer to the North Pole. There are 90 degrees of latitude north of the equator and another 90 circles of latitude south of the equator. The trade winds blow in two paths. One belt begins just north of the equator and the other just south of the equator. These pathways reach to latitudes 30 degrees north and 30 degrees south.
If our big planet did not spin on its axis, the two trade winds would blow straight toward the equator from the north and the south. But the spinning earth bends or twists the planetary winds. The north and south trade winds are twisted to blow somewhat from the east. In the northern half of the world, the trade winds blow toward the equator from the northeast. In the Southern Hemisphere, the trade winds blow to the equator from the southeast.
Day and night the trade winds blow steadily around the globe. Their wide belts begin at latitudes 30 degrees north and south and reach almost to the equator. Most of North America is above latitude 30 but this line crosses near Jacksonville, Florida. The part of Florida south of Jacksonville is in the trade wind belt where the planetary winds blow steadily from the northeast.
Winds are moving masses of air. The air tries to mix up its light and heavy masses to make them even. The heavy masses tend to flow and blow into pockets of lighter air. The sun warms the equator and the warm air above it swells up and becomes thin and light cooler air from father north and south blows in to fill up the belt of light air over the equator. This starts the trade winds blowing and the spinning earth twists them to slant toward the equator from the northeast and the southeast.