198 



SYMPOSIUM ON AERONAUTICS. 



winds where the latter flow over the trades, while cyclones and 

 anticyclones have the speed and direction of the upper westerlies. 

 The data seem to show that cyclonic disturbances form on the left 

 side of oppositely directed, passing currents of air in the surface 

 stratum, while anticyclonic disturbances form on the right side. The 

 airs in these two sorts of currents are differently tempered and of 

 different moisture content, the extent of these differences having 

 to do with the intensity of the disturbances. These irregularities 

 in pressure distribution behave toward the upper westerly wind, or, 

 in the case of tropical hurricanes, toward the antitrades, as varia- 

 tions in the level of the surface over which they flow. The dis- 

 turbances are thus communicated directly to the upper winds which 



Fig. 10. Mean of Wind Observations in " Highs " at 3000 Meters above Sea 



Level, 1907-1912. 



