Man's physical universe

xanabras

UNIT III

SECTION 2

THE NATURE OF THE EARTH INTRIGUES THE

CURIOSITY OF MAN

Introduction.

It is only natural that the insatiable curiosity of modern man should

lead him to explore every portion of the earth's surface, often risking

starvation or freezing to death in Arctic and Antarctic explorations,

or putting his last ounce of strength into the attempt to climb just

one foot higher on Mount Everest. Marvelous underground caverns,

fuming volcanoes, tropical jungles, and desert "no-man's lands"

having been conquered, man next directed his curiosity to vertical

explorations of the three spheres: the gaseous envelope, called the

atmosphere ; the liquid layer, called the hydrosphere ; and the solid

The fact that these three layers — solid,

lithosphere and centrosphere.

liquid, and gaseous — are in contact with each other and are heated

by the sun is responsible for the continuous changes in the surface of

the earth. It is at this point of contact of land, water, and air that man

has lived.

This section will attempt to outline briefly how man has been able

to explore these three spheres and what he has learned about them.

The Atmosphere Consists of the Troposphere and the Stratosphere.

The duration of twilight indicates that the atmosphere reaches to a

height of about 40 miles. Meteor flights give evidence that there is

some atmosphere as high as 90 to 185 miles.

Auroral displays suggest

that the atmosphere dwindles down to a very low density at a height

of 600 miles.

The stratosphere is that portion of the atmosphere which lies above

the region of circulation. Lack of circulation results in few clouds or

weather disturbances in this region.

The troposphere is the region near the earth where there is continual

disturbance, and the tropopause separates the troposphere from the

stratosphere. The tropopause is about 11 miles high over the equator

and 4 miles high over the poles.

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