KITE WORK OF THE WEATHER BUREAU 57 



destro3'ing the synchronism of the observations, without which aerial 

 observations would be of little assistance to the forecaster in his work. 



However disappointing the results obtained ina}'' have been when 

 viewed from the standpoint of weather forecasting, they were very 

 far from being so from another. An immense amount of data was 

 obtained from the 1,217 ascensions and 3,835 observations, particu- 

 larly in reference to temperature variations with increase of altitude, 

 and it is believed that our previous knowledge of this subject has been 

 materially increased. 



Briefly summarized, the results of the observations were as follows : 



There were considered in all 3,835 observations, of which 603 were 

 at 1,000 feet elevation, 906 at 1,500 feet, 928 at 2,000 feet, 746 at 3,000 

 feet, 423 at 4,000 feet, 182 at 5,000 feet, 38 at 6,000 feet, 7 at 7,000 feet, 

 and 2 at 8,000 feet. Of the two at 8,000 feet, one was obtained at 

 Washington, D. C, and the other at Dodge City, Kans. In tlie Mis- 

 sissippi Basin, except on the slope of the Rocky Mountains, high 

 ascensions were impossible, as the average wind velocity was but six 

 miles or less per hour. 



The mean rate of diminution of temperature, with increase of alti- 

 tude, was found to be 5 degrees for each 1,000 feet, or only 0.4 degree 

 less than the true adiabatic rate. This is strictly a mean value, ob- 

 tained from observations taken at all elevations from 1,000 to 8,000 feet 

 and under varying conditions of weather and at different hours. 



The largest gradient, 7.4 degrees per 1,000 feet, was found up to 

 1,000 feet, and thence up to 5,000 feet there was a steady decrease to 

 3.8 degrees, the rate of decrease varjnng inversely with the altitude. 

 Above 5,000 feet there was a tendency toward a slow rise in the gra- 

 dient, l)ut the lack of a sufficient number of observations above 6,000 

 feet prevents a positive assertion to this effect. The morning gra- 

 dients were also greatest up to 1,000 feet, and least up to 5,000 feet, 

 and the rate of decrease was about the same as that of the mean, the 

 curves showing a very close agreement in this respect. The average 

 morning gradient was 4.8 degrees per 1,000 feet. 



The afternoon gradients were larger, but not decidedly so, the aver- 

 age value being 5.8 degrees per 1,000 feet. The greatest rate of de- 

 crease is still found at 1,000 feet, and the least up to 5,000 feet, if the 

 few observations at 7,000 feet are not given equal weight. 



The morning, afternoon, and mean gradients for the different ele- 

 vations from 1,000 to 8,000 feet are given in the following table : 



