1 28 Fads in Meteorology. 



Thunder storms appear to be whirlwinds, gyrating, in ordinary ca- 

 ses, on a horizontal axis of rotation. The wind which they exhibit 

 often blows with a velocity greatly exceeding the progress of the 

 thunder storm, as is the case with other whirlwind storms. 



The presence of warm and humid air is supposed to be necessary 

 to the production of violent electrical phenomena, such as thunder 

 and lightning. The latter phenomenon is generally caused by the 

 commingling of air, of different temperature and condition. 



Hurricanes are the most violent and destructive storms of the At- 

 lantic ocean. They are of the whirlwind character, and the direc- 

 tion of their rotation in the North Atlantic is from right to left, hori- 

 zontally. In the latitudes of the West Indies, their general course or 

 drift is towards the west inclining, however, gradually to the north- 

 ward. About the parallel of 30° their progress to the westward 

 ceases, and passing into higher latitudes they pursue an easterly 

 course, on a track nearly parallel to the American coast. 



In the West Indies, hurricanes begin to blow from a northern quar- 

 ter of the horizon, and thence changing to the west and round to a 

 southern quarter, and then their fury is over. These phases however 

 will be found somewhat different towards the two opposite margins 

 of a st6rm's track, and also in positions which are sheltered in sotne 

 directions from the action of the storm by elevated land. On the 

 coast of the United States these storms commence blowing from an 

 eastern quarter, which corresponds to the change in their line of prog- 

 ress, and exhibiting changes of a like character, they terminate with 

 fair weather from a western quarter. 



The direction of the wind and the progressive changes in great 

 storms are found to accord with the locality or position of the storm 

 in the great oceanic circuit of wind or atmospheric current. In the 

 southern hemisphere the course and changes of such storms appear 

 to be counter 1o those in the. northern hemisphere. Thus storms in 

 the northern latitudes in certain circumstances blow first from the 

 south-east and then change to the north-west ; while in New-Holland, 

 storms in like circumstances blow first from north-west and then 

 change to south-east. 



Elevated Currents^ and Stratification of the Atmosphere. 



Little is known of the direction of the wind upon the highest 

 mountains, but in Peru and at the Sandwich Islands, at the height of 

 about eighteen thousand feet, it has been found to be fresh from the 



