The Structure of the atmosphere
That the atmosphere extends from the earth’s surface upward is obvious. But where does the atmosphere end is rather an intriguing question. If we consider the changes in atmosphere with height, some very interesting facts come into light.
We know that at sea- level the average pressure is a little more than 1000 millibars. But the pressure at higher altitudes is less. By examining it is clear that one-half of the atmosphere lies below an altitude of 5.6 kilometers.
About 16 kilometers above the surface of the earth, about 90 percent of the atmosphere has been covered. Beyond this level, the atmosphere is found in an extremely rarefied state.
The rate of decrease in the atmospheric pressure is highly variable. The fact is that pressure decreases at a decreasing rate with an increase in altitude.
Beyond an altitude of about 50 kilometers, the pressure decrease is rather negligible. In other words, traces of the atmosphere extend up to thousands of kilometers beyond the earth’s surface.
