128 Facts 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 westwar 
ceases, and passing into higher latitudes they pursue an. easterly 
course, on a track nearly parallel to the rican coast. 
In the West Indies, hurricanes begin to blow from a northern quar- 
ier 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 storm’s track, and also in positions which are sheltered in some 
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 changer; abey terminate with 
fair weather from a western quarter. — 
The direction of the wind and the progressive changes i in arent 
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 to 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 cireumstances 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 
