Geography of the Air. 157 



regions substantially two-thirds of the storms of the Northern 

 Hemisphere occurred ; while between the parallels of 45° and 55°, 

 north, 36 per cent, of the entire disturbances ai*e recorded. The 

 most remarkable belt of storm frequency on the Northern Hemi- 

 sphere is that extending from the Gulf of Saint Lawrence west- 

 ward to the extreme end of Lake Superior, as nearly 8 per cent, 

 of all the storms of the Northern Hemisphere passed over this 

 limited region ; the maximum frequency (1.2 per centum) oc- 

 cui-ring over the 6-degree square northeastward of Lake Huron. 



As regards longitudinal distribution, an unusually large pro- 

 portion of storms prevailed between the 50th meridian and 105th 

 meridian, west ; 37 per cent, or one-third of all the storms of 

 the Northern Hemisj)here occurring within this region. A 

 second belt of comparative storm frequency obtains from the 

 meridian of Greenwich eastward to the 30th meridian ; over 

 which region 15 per cent, of the entire number of storms occurred. 



Only four hundred, or less than 9 per cent, of the entire 

 number of storms, entered the American continent from the Pacific 

 ocean, while about thirteen hundred storms, excluding the West 

 India hurricanes, passed eastward off of the American continent. 

 Over nine hundred storms entered Europe from the Atlantic 

 ocean, of which probably four hundred and fifty, or ten per 

 cent, of the whole number recorded, were developed over the 

 Atlantic ocean. Probably not thirty storms, or less than three per 

 cent, of those which entered Europe from the Atlantic, crossed 

 over the continents of Europe and Asia to the Pacific ocean. 

 Fully two-thirds of the storms which enter Europe from the 

 Atlantic are dissipated as active stoi'm-centres before they reach 

 the Asiatic frontier. 



The tendency of great bodies of water, when surrounded wholly 

 or largely by land, to generate storms or facilitate their develop- 

 ment, is evident from the unusual prevalence of storms over the 

 great lakes, the St. Lawrence bay and the Gulf of Mexico in 

 North America ; over the North and Baltic seas. Bay of Biscay 

 and the Mediterranean in Europe ; the Bay of Bengal, and over 

 the China and Okhotsk seas. 



Undoubtedly a considerable proportion of these storms are drawn 

 towards these regions owing to the effect of evaporation upon the 

 humidity and temperature of the superincumbent atmosphere, so 

 that a very considerable proportion of the storms credited to these 

 squares have not originated therein, but have been drawn up from 



