252 Phenomena and Causes of Hail Storms. 



and the other south from the 50th degree of north latitude, 

 each being at an elevation of 10,000 feet above the earth ; and 

 we have found them sufficient to explain the occurrence of vio- 

 lent hail-storms within the temperate zones, at least in our own 

 latitude ; other opposite points may be assumed for other lati- 

 tudes. But suppose we transfer this reasoning to the equator, 

 and consider the condition of two opposite winds blowing from 

 ten degrees on either side, and meeting at the equator, each be- 

 ino- at the same elevation of 10,000 feet above the earth. Now 

 both of these winds would be warm, and almost equally so, and 

 here of course would be wanting that intensely cold current 

 which we have been able readily to summon to our aid to help 

 in forming our hailstones in the temperate climate. If we take 

 any other point within tlie torrid zone, the case would be indeed 

 somewhat less unfavourable to the production of hail ; the op- 

 posite currents might diffi^r in temperature to a degree sufficient 

 to account for the formation of clouds and rain, and thunder 

 and lightning ; but in this region we know not when to look for 

 ihsiijreezmg current, unless we ascend so high that there no 

 hot air exists, holding watery vapour to be frozen by it. The 

 case is plain, that if we ascend in the torrid zone for air that is 

 cold enough to answer our purpose, we ascend above the region 

 of the hot air, the watery vapour of which is necessary to affiard 

 the materials for hail ; whereas, in our own latitude, on ascend- 

 ing to the region of congelation, we find the north and south 

 currents differing in temperature, more than opposite winds in 

 any other part of the globe. There is indeed one situation 

 where we may imagine hail to be formed within the torrid zone, 

 and that is in the vicinity of lofty mountains covered with snow ; 

 and there, in fact, it does sometimes hail *. 



Next, if we attentively consider the circumstances of the 

 frigid zone, we shall see that here there is no hot region on 

 the one side to send its heated air to mix with the cold currents 

 from the other ; and that no meeting of very cold with warm 

 winds could possibly take place. The rain, indeed, on account 

 of the ordinary cold of this region, would frequently descend 

 in the form of hail ; but it would necessarily be of that small 



• Ediu. Encyc. vol. xv. Art. Phys. Geogr. at an elevation of 1500 or 

 2000 feet. 



