ABSTRACTS 



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METEOROLOGY. — Free air data, sounding balloon ascensions at Indi- 

 anapolis, Omaha, and Huron. Wm. R. Blair. Bulletin of the 

 Mount Weather Observatory, 4: 183-304. 1911. 



Four series of sounding balloon ascensions, giving 79 good records, 

 were made by the U. S. Weather Bureau at the above places during the 

 years 1909, 1910 and 1911. One of these ascensions, the one made at 

 Huron, S. Dak., Sept. 1, 1910, is the highest on record, 30,486 meters. 



The data obtained from all these ascensions, temperature, pressure, 

 humidity, height, wind velocity and wind direction, are given in detail 

 in a number of tables and diagrams and the final summary and dis- 

 cussion include 59 additional ascensions made at St. Louis, Mo., and at 

 Pittsfield, Mass by the Blue Hill Meteroological Observatory. 



Among the conclusions reached are: 



a. Rapid changes of condition with altitude seem to occur at eleva- 

 tions of about 1.2, 3.5, 10.5, 15.5, and 28.0 kilometers. That is to say, 

 at the upper limit of diurnal convection, upper level of the lower con- 

 densation layer, average level of the upper condensation layer, upper 

 limit of condensation, and a much higher level, respectively. 



b. The first and second of the above levels and the third over rising 

 air pressure at the earth's surface are at greater elevations in summer 

 than in winter; the fourth level is highest in spring and lowest in autumn. 



c. The change in temperature with altitude is increased, with a rising- 

 barometer, up to the first level; decreased from the first to the second, 

 and at higher levels not much affected. 



d. At the third level the temperature decreases slowly with altitude, 

 at the fourth it increases and at the fifth it again decreases. 



e. Air temperatures are lower above the third level and higher below 

 it with a falling than they are with a rising barometer. 



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