October 29, 1920] 



SCIENCE 



411 



the data from soundings of the upper air are 

 becoming available in fairly large quantity, 

 it is necessary to engage in a careful study to 

 determine the most profitable and intelligent 

 way to use them. In recent years, aerological 

 work has been steadily advancing to its place 

 in the forefront of meteorological endeavor, 

 and to-day most national meteorological serv- 

 ices have established, or are establishing, aero- 

 logical divisions. In other words, it is real- 

 ized that probably the real controls of surface 

 weather lie somewhere in the upper air. 



The first aerological work in the United 

 States was done at Blue Hill Observatory, 

 near Boston, under the directorship of Rotch. 

 In 1907, the United States "Weather Bureau 

 established a station at Mt. Weather, Vir- 

 ginia. That station, which has a record of 

 frequent kite flights and aerial soundings 

 by captive balloons, was discontinued after 

 seven years. Other stations have been estab- 

 lished, however, at Drexel, Nebraska; Ellen- 

 dale, North Dakota ; Broken Arrow, Okla- 

 homa; Groesbeck, Texas; Royal Center, In- 

 diana; and Leesburg, Georgia. The data 

 from the many thousands of kite flights made 

 at these stations have been and are being 

 published in the Supplements of the Monthly 

 Weather Review. These data include tem- 

 peratures, pressures, moisture content, wind 

 speed and direction, at various levels in the 

 free-air. It should be said, however, that one 

 of the inherent features of kite data is that 

 they represent conditions in moderate winds 

 only, since kites can not be flown in very 

 light or very strong winds. 



A convenient summary of the work of the 

 Drexel Aerological Station was recently pub- 

 lished in the Monthly Weather Review.^ The 

 purpose of the summary, says Mr. Gregg, is 

 " to present in brief and convenient form for 

 the information and use of artillery and 



1 Gregg, Willis Bay, ' ' Average free-air condi- 

 tions as olDserved by means of kites at Drexel 

 Aerological Station, Nebr., during tlie period No- 

 vember, 1915 to December, 1918, inclusive," 

 Monthly Weather Review, January, 1920, pp. 1-11. 

 Eeprints may be obtained upon application to the 

 Chief of the Weather Bureau, Washington, D. C. 



aviation services the results of free-air obser- 

 vations that have been secured by means of 

 kites at Drexel, Nebraska." There are many 

 tables and charts. The values obtained are 

 the means of 1,074 kite flights. The author, 

 in his synopsis, says: 



A discussion of the reliability of the data indi- 

 cates that instrumental and observational errors 

 have been largely eliminated; that the monthly 

 distribution is good; that the diurnal distribution 

 is less satisfactory, but probably fairly representa- 

 tive, at any rate for all levels a short distance 

 above the surface; but that, owing to the short- 

 ness of the period under consideration and its 

 wide departures at times from normal conditions, 

 some of the monthly means can not be considered 

 as normal values. These irregularities largely dis- 

 appear, however, in the seasonal and annual aver- 

 ages; and the latter, especially, may be accepted 

 as closely approximating true conditions. 



Now that a number of years' data have 

 accumulated, what are the benefits which may 

 accrue from a study of them? Among others, 

 there are two problems, which may be con- 

 sidered: one is of immediate importance, the 

 other is an old one, long recognized, but at- 

 tacked only at rare intervals, and with vary- 

 ing success. The first concerns itself with 

 forecasting for aviation, the second with the 

 reduction of pressure in the Plateau region 

 of western United States. They represent 

 only two of the many problems, the solution 

 of which aerological data may aid. 



A paper on the question of making pressure 

 maps for stated levels in the free-air as aids 

 in forecasting winds aloft for the use of 

 aviation and as a suggested panacea for the 

 long-recognized reduction difiiculties in west- 

 ern United States, has just appeared.^ The 

 central idea about which the work is built is 

 that the Laplacian hj^psometric formida re- 

 quires a value to be substituted for the term 

 representing the mean temperature of the air 

 column which exactly satisfies its definition. 

 Reductions to sea-level obviously can not do 



2 Meisinger, C. LeEoy, ' ' Preliminary Steps in. 

 the Making of Free-air Pressure and Wind 

 Charts, ' ' Monthly Weather Review, M.a.j, 1920, pp. 

 251-263. 



