The Scientific Scrapbook

Using a new type of meteor speedometer which makes possible the best approach to the tangled and much disputed problem of temperatures in the upper air, Dr. Fred L. Whipple, instructor in Astronomy, has shown conclusively from the flaming paths of meteors that there are two high temperature layers in the stratosphere.

These layers are at heights of about 38 and 70 miles, and higher, above the earth. At 38 miles the temperature is about 100 degrees Centigrade, the boiling point of water; at 70 miles about 20 degrees Centigrade, ordinary room temperature.

Contradicts Old Theories

Most laymen and many scientists think the stratosphere is a cold expanse of thinning air extending above the six miles of aerial dregs (the troposphere) in which we live. Balloon observations also give no evidence that the temperature of the stratosphere is anything but icy cold and uniform, at about 55 degrees below zero Centigrade.

In the past quarter century certain phenomena, such as sound reflection, tidal conditions in the upper air and visually traced meteor paths, have led a few scientists to believe that the conditions observed can be explained only by hot layers in the stratosphere. Direct evidence has been lacking. Nobody knows why there should be hot layers.

With his new apparatus Whipple has been able to obtain very accurate measurements of the height, brightness, velocity and slowing down of meteors as they flash about 30 to 60 miles above the ground. From these factors it is possible to derive very accurately the density of the air at various heights.