KITE WORK OF THE WEATHER BUREAU 61 



call}' the same, the differences being confined to a deflection toward 

 the right at the kite. This deflection frequently increased with the 

 altitude, but rarely exceeded 90 degrees. In some few instances the 

 kite was deflected toward the left, but not to any great extent. When 

 the deflection was toward the left, the wind velocity decreased with 

 increase of altitude, as shown by the diminished pull on the kite wire. 

 As a matter of interesting coincidence, and without intention of en- 

 deavoring to establish a direct relation of cause and effect between 

 the two, it may also be stated that these deflections toward the left 

 were quite frequently followed b}^ thunderstorms within a few hours. 



At Duluth, Minn., there were occasionally wide divergencies of the 

 kite toward the left, due to the northeast wind from Lake Superior. 

 This nortlieast wind was very often purely local, attributable entirely 

 to the influence of the lake, and corresponding in a minor way to the 

 sea i)reeze.s of the ocean shores. It developed upon investigation that 

 these local currents were sometimes not more than 700 or 800 feet in 

 depth, and rarely more than 2,000 feet. 



Hammon * and McAdie recorded a somewhat similar experience 

 with tlie westerly surface winds at San Francisco during their kite 

 experiments in 1896, and in his paper on the subject Mr Hammon 

 concluded that the strong westerly surface wind which prevails on the 

 Pacific Coast nearly ever}' afternoon has a depth of only 800 to 2,500 

 feet. 



An extension of the aerial observations to other seacoasts would 

 doubtless prove conclusiveh' that the diurnal sea breezes are extremely 

 shallow. 



After November, 1898, all kite stations were closed except that at 

 Pierre, S. Dak., where ascensions were made whenever possible dur- 

 ing tlie 3'ear 1899, and still continue. No extended study of the ob- 

 servations made during this time has as yet been made, but a cursor}' 

 examination of the winter temperature records discloses a condition 

 of affairs radically different from that which prevails during the re- 

 maining seasons of the year. The inversions are very frequent and 

 decidedly marked. Indeed they are so persistent during the colder 

 weather as to lead to the inevital)le conclusion tliat during a cold 

 wave the belt of cold air is not much over one mile in height, and 

 often but little over half a mile. 



On several days it was also nuticed that there were at least three 



* Kxix-rimcnts with Kiti's at Sun Kiam-isi'o, Cal., Iiy \V. H. Haiiiriiuii, tVn-eoiisI uttiL-iul. 

 MiiMlhl\- \V<mi1m-i- Itc'vicw. .\iiKii><<. IX'M. 



