WEATHER BUEEAU. 157 



phenomenon. It was discovered in northern Europe, and its pres- 

 ence has since been estabhshed in the United States, within the 

 Arctic Circle, north of Euro|)e, over tropical Africa and the Indian 

 Ocean, and in Java. 



The matter which follows is largely taken from a preliminary 

 re])ort on the data secured by sounding-balloon ascensions in the 

 United States. The full report vnW be published in the Mount 

 Weather Bulletin, Volume IV, probably in part 3, which will be sent 

 to press in August, 1911. The statements refer to the most obvious 

 facts ascertained by the balloon ascensions. 



The original plan of sounding-balloon ascensions in this countr}^ 

 contemplated simultaneous ascents from two points on an east and 

 west line. Notwithstanding the great area of the United States, 

 regions adapted to the work are remarkably few, outside of the 

 Western Plains and the Central Mississippi- Valley. Fort Omaha, 

 Nebr., was selected as the western station largely because of the pres- 

 ence there of a detachment of the United States Signal Corps, whicli 

 maintains a hj^drogcn-gas plant. The thanl^ of the bureau are due 

 to Gen. James Allen, Chief Signal Officer, and the local officials at 

 Fort Omaha, for many courtesies shown while operations were con- 

 ducted at that point. Indianapolis, Ind., was selected as the eastern 

 station. The board of public parks of that city kindly placed at our 

 disposal ground in the park system on which to conduct the ascen- 

 sions. For various reasons the number of ascensions at this place 

 was less than at Fort Omaha, but all of the balloon meteorographs 

 sent up were eventually found and returned to Mount Weather. 



The second and fourth series of ascensions were made at Fort 

 Omaha, Nebr. In the second Omaha series the balloons used had 

 been on hand about six months and the rubber had so deteriorated 

 during that time that heights much above 6,000 meters (3.7 miles) 

 were not attained. 



The third series was made at Huron, S. Dak. The advantages of 

 the latter station lie in its geographic position, being farther north, 

 and thus more directly in the path of cyclonic and anticyclonic areas. 

 A successful series of ascensions was made from the State fair grounds 

 at Huron, 24 of the 26 instruments sent up being recovered. 



During the fourth and last series of ascensions, at Fort Omaha, 

 from February 8 to March 4, 1911, inclusive, 25 meteorographs were 

 sent up, of which 22 were found and returned. This was also an 

 excellent series, but unfortunately no well-marked cyclonic areas 

 passed over Fort Omaha during the three weeks the party was there. 



Naturally the first thought in connection with the upper inversion 

 is its relation to terrestrial weather conditions. Thus far ideas on 

 the subject are quite hazy, but certain facts have been established, 

 as follows: The lowest tem])eratures of the upper inversion are found 

 in equatorial regions and the highest in the middle latitudes. In 

 other words, tem])erature increases with increase of latitude, con- 

 trary to the rule which prevails on the earth's surface. In tro])ical 

 Africa, Berson, of the Gorman expedition, found a temperature of 

 -83.9° C. (-119° F.) at an altitude of 19 kilometers (11.8 miles).* 

 At the same elevation in the United States the temperatures range 



' Later ascensions made at Java, Batavia, confirm the existence of low temperatures over equatoriul 

 regions. See van Bemmelin in Met. Zeit., Ma^, 1911. 



