8 Phenomena and Causes of Hail Storms. 



We will now see how far the foregoing explanation corresponds 

 to the facts hefore enumerated. 



Why then are violent hail storms attended by all the other elements 

 of storms^ — hy clouds of intense blackness^ and terrific thunder and 

 lightning^' Because the sudden concourse of a wind exceedingly 

 cold with one comparatively hot, ought, in conformity with the known 

 causes of these phenomena, to exhibit them in their most energetic 

 forms. All these atmospheric phenomena are linked together, and the 

 same cause acting with different degrees of energy, produces each of 

 them in its turn. The mixing of portions of air differing but little in 

 temperature is sufficient to form clouds — :f the temperature differs 

 somewhat more, the watery vapor may fall in rain — if the one portion 

 is hot and the other cold, more sudden and powerful rains are the 

 consequence, and thunder and lightning result from the rapid conden- 

 sation of watery vapor — and finally, when a powerful wind from the 

 regions of perpetual frost, mixes with the heated and humid air of 

 a warmer sky, the same watery vapor descends in hail. 



Why are such violent hailstorms confned to the temperate climates^ 

 and ivhy do they occur neither in the torrid nor in the frigid zone 9 

 This is a point of great difficulty, and the question has never to my 

 knowledge been satisfactorily answered ; but I think we perceive 

 something in the foregoing principles, which may lead us to a cor- 

 rect understanding of it. We have considered the case of two 

 opposite winds from points differing twenty degrees in latitude, 

 one blowing north fi'om the oOrii, and the other south from 

 the 50ih degrfee of north latitude, each being at an elevation of 

 lOjOQO feet above the earth; and we have found them sufficient to 

 explain the occurrence of violent hail storms within the temperate 

 zones, at least in our own latitude j other opposite points may be as- 

 sumed for other latitudes. But suppose we transfer this reasoning to 

 the equator, and consider the condition of two opposite winds blow- 

 ing from ten degrees on either side, and meeting at the equator, each 

 being at die 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 

 hailstone in the temperate climate. If we take any other point with- 

 in the torrid zone, the case would be indeed somewhat less unfavor- 

 able to the production of hail ; the opposite currents might differ in 

 temperature to a degree sufficient to account for the formation of 



