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Show The Earth's Envelope. The new science of the air is the result re-sult of many hundred kite and sounding sound-ing balloon flights made by day and by night in fair weather and foul, over land and sea, at all seasons of the year and from the equator to the arctic circle. cir-cle. Most people know that the warm air surrounding the earth is only a thin belt, but we do not most of us know that at ten miles above the earth it would not only be bitterly cold, but the sun would appear quite different. The air is stratified in three more or less distinct layers. In the lowest we live. It extends about two miles and is a region of turmoil, whimsical winds, cyclones and anti-cyclones. At two miles the freezing point is reached, and then there is a second stratum extending extend-ing upward for about another six miles. Here the air grows steadily colder and drier, the lowest temperature recorded being 167 degrees below freezing point. Here the air moves in great planetary swirls produced by the spinning of the earth on its axis, so that the wind always al-ways blows in the same easterly direction. direc-tion. The greater the height the more furious fu-rious is the blast of this relentless gale. After this layer comes the thiid or iso thermal stratum, discovered almost simultaneously by M. de Bort and Dr. Assmann. This is called the permanent perma-nent inversion stratum, because the temperature increases with the height reached. But the temperatures so far recorded in the .second stratum are not high, being far below zero Fahrenheit, generally somewhere from 1"2 degrees to 140 degrees below it. Here the air no longer swirls in a planetary circle. The wind may blow in a direction contrary to that in the second layer. And the air invariably is excessively dry. AVhere this third stratum ends no one knows. But it must be at more than eighteen miles above the earth. For sounding balloons bal-loons have reached this height and have not found the end of the permanent perma-nent inversion layer of air. AArhen the influence of the upper regions of air upon the lower is fully understoood it may be possible to foretell the weather not merely for a day, but for a week. |