264 ANNUAL llEPORTS OF DEPARTMENT OE AGRICULTURE. 



highest kite flights ever made, and, what is more important, nearly 

 continuous daily flights. Some of the flights were made under try- 

 ing conditions. During the prevalence of fog, rain, snow, or high 

 winds practically all of "the flights were low, the meteorograph at such 

 limes being carried barely beyond the influence of the mountain top. 

 Under adverse as well as favorable conditions the work was carried 

 on, and it has been shown beyond doubt that at times the meteorologi- 

 cal conditions disclosed by kite flights shed light upon the problem of 

 weather forecasting. The work has thus been justified on the ground 

 of its usefulness in forecasting, as well as on the broader ground of 

 a Hording a substantial addition to the sum of our knowledge respect- 

 ing the conditions that exist in the air some distance above the earth's 

 surface. 



Three series of continuous kite flights were made by day and by 

 night during the year, with a view of obtaining further information 

 regarding the diurnal variation of temperature in the free air with 

 increase in altitude. More observations of this character are needed 

 in order to fix with some definiteness the altitude in the free air to 

 which the diurnal warming and cooling, respectively, extend. 



In addition to the current work of daily kite flights, a report on the 

 sounding-balloon ascensions made in western States in 1909, 1910, 

 and 1911 has been completed and given publication as part 4, Volume 

 IV, of the Mount Weather Bulletin for 1911. These ascensions were 

 made, it may be remembered, for the purpose of exploring the air 

 strata mostly between 3 and 15 miles above the earth's surface. Up 

 to 3 miles above the surface of the earth independent explorations of 

 the atmosphere have been extensively carried on by means of kites 

 and captive balloons at Mount Weather, Va., and Blue Hill, Mass., in 

 this country, and at many places in the British Isles and on the Conti- 

 nent of Europe. The conditions existing above the 3-mile level form 

 an international problem in the solution of which the meteorological 

 services of practically all civilized countries are engaged. The report 

 already mentioned includes a discussion of the records of 138 

 sounding-balloon ascensions, 79 of which were made by the Mount 

 Weather Observatory and the remaining 59 by the Blue Hill Ob- 

 servatory, thus uniting in one publication all of the high-level meteor- 

 ological observations made in the United States. On the whole, this 

 report forms the most important contribution to the meteorology of 

 the higher atmosphere thus far made at Mount Weather. The atmos- 

 pheric conditions at extremely high levels, as disclosed by these 

 records, are not wholly in'accord with the conditions found to exist at 

 similar levels above the Continent of Europe, where the upper levels 

 of the atmosphere have been more thoroughly explored. It is evident 

 that in the United States only a good beginning has thus far been 

 made in the exploration of the upper levels of the atmosphere, and 

 that the" phenomena observed and discussed in the report need further 

 confirmation before we can consider them as being founded on 

 sufficient observational data. 



Temperatures on mountain tops and in adjacent valleys. — 

 Studies of temperature conditions on mountain tops and in the 

 adjacent valleys at Mount Weather and elsewhere have been con- 

 tinued and the results have appeared in the Mount Weather Bul- 

 letin. In general, these studies have tended to fix the relation be- 



