Bulletin of the Mount Weather Observatory Volume 4 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ...par. 2). It does show a decidedly greater drop in temperature, from the temperature of the lower air strata, in the summer than in the winter months. If, instead of the grouping used in Table IX, the 46 observations be grouped into (1) those made within areas of high pressure and (2) those made within areas of low pressure, the altitude of the surface S is found to be about the same in both groups--somewhat higher in the low-pressure areas than in the high. It is not easy to see why there should be any difference in the altitude of S in these two groups, and the one found may be attributable to the distribution of the observations. Others have used this grouping in the discussion of their observations and have found the surface S higher in high-pressure areas and lower in low. Having accepted this finding as a universal fact, Prof. Humphreys has offered an explanation for it (this bulletin, Vol. II, p. 16, par. 4). But the fact does not seem to be universal, and the grouping is not a characteristic one when applied to the observations that have been made at Indianapolis, Omaha, and Huron. The differences shown in Table IX are apparently too large to be attributed to the distribution of the observations in the groups there compared. THE SURFACE OF MINIMUM TEMPERATURE. The surface of minimum temperature is about 5 kilometers higher up than the surface of maximum change with altitude in vertical temperature gradient, and the number of observations is consequently considerably less. What observations there are seem to show that both surfaces rise and fall with falling and rising air pressure, respectively, at the earth, s surface and with the seasons over rising air pressure. They seem to be farther apart in the summer than in the winter.