Frank Pardi, age 10, of Spokane, Wash., for his question:

WHY IS THE EQUATOR SO HOT?

We tend to think that the equator is a steamy jungle, crowded with tropical trees and chattering monkeys. But this is only part of the picture. Most of the equator runs over the sea. At other points along the line there are grassy plains and even a few mountain peaks that wear snowy caps all through the year.

The equator runs around the wide waist of the world exactly halfway between the North and South poles. It crosses South America, Africa and part of Indonesia  but most of it is over the oceans. It is a thin line and there is a wide tropical belt on each side. Next, there are the two temperate belts and the cold polar regions are at opposite ends of the world.

Since the equator is farthest from the cold poles, we might expect it to be the hottest place in the world. But sometimes things are even hotter in the tropics. In most places along'the equator people expect a warm summer day   every day of the year. Every day lasts 12 hours and so does every night. There are daily showers but the only winds are gentle breezes

The earth gets its warmth from the sun and the sun shines down on the whole world. But there are several reasons why some places get more warmth than others. Our temperate zone is warmer during the long summer days, when the nights are short. We get less warmth during the short winter days. Even in summer we cool off when chilly winds blow in from afar. At the equator all the days are equal and there are no chilly winds.

But the path of the sun is even more important. Every day it climbs to its highest point in the noonday sky. And the higher it gets, the more warmth it sheds down on the earth below. At the equator, the noonday sun always climbs higher than even our midsummer sun. And twice each year, in March and September, it reaches the very top of the sky, directly overhead. This highest high point is the zenith in our temperate zone, even on midsummer days.

Plant life thrives in warm sunny weather and plenty of moisture. This is why there are dense steamy jungles along parts of the equator. But higher up the weather is always cooler. In South America at the equator, the tall peaks of the Andes are capped with snow all through the year.