THE TERRESTRIAL ATMOSPHERE.

Evening Post, Volume LXXVIII, Issue 57, 4 September 1909, Page 10

THE TERRESTRIAL ATMOSPHERE.

" The higher we go the colder it gets " used to be the convincing sentence in which a fond parent might sum up for his child an article flf meteorological faith. But of recent years the observations which are being industriously collected by means of ballons-sondes have tended to throw considerable donbt on the general truth of the statement. It has been proved that at heights of from seven-and-a-half to nine miles the decrease of the temperature is actually checked. Mr. Humphreys, in the Bulletin of the Mount Weather Observatory, interprets the results as follows. He divides the atmosphere into three more or less distinct regions. First, that which extends to a height of about ten thousand feet. This is the densest regjpn ; tho winds are irregular, arid their direction mainly depends on the relative positions of the high and low-pressure centres. The temperature decreases irregularly, and not unfrequently do we find an increase with the height. The second region, which runs up to ten thousand yards, is one in which the decrease of the temperature takes place much more regularly. This is now above the strata in which those clouds are formed which give us fain or snow. The' centres of high and low pressure are now exerting far less influence on the direction of the winds. The velocity of the wind increases, but the movements of the atmosphere are now conforming to the general laws of circulation. As a whole it is a stable region, as may be inferred from the absence of clouds and the regular decrease of temperature, but there are sometimes vertical movements of variable extent and intensity. When we enter the last of the three regions the temperature increases with the height. Here the air is very dry, and the speed of the wind is far less than in tho region below. Vertical movements of convection cannot exist here, because 1 the temperature increases with the height. ' Mr. Humphreys concludes th»t the earth is surrounded by two distinct and superposed atmospheres. In the lower take place the disturbances that produce change of weather. Here is two-thirds or even three-quarters of the total mass of oxygen and nitrogen, an even larger proportion of carbonic acid gas, and almost all the water vapour. The higher atmosphere lies on the lower almost as oil floats on water. All of which rather upsets our preconceived notions of the nature of the terrestrial atmosphere. — Westminster Gazette.