BLAIR— AEROLOGY. 



207 



Fig. i8. Temperature distribution in lows observed at Mount Weather. 



The gustiness of the wind is also a source of some difficulty to 

 the aeronaut. This is especially true of surface winds because here 

 the gusts follow each other at shorter and less regular intervals than 

 do those occurring in winds at the higher levels. Each gust con- 



FiG. 22. Record of wind speed and force by pressure tube anemometer. 



