Climatology of the United States. 245 
a violent winter storm, is the ane half of the atmosphere, an 
the month of January on the parallel of 40° is about 82°. 
ase of temperature as we ascend is about one degree of 
Fahrenheit for 300 feet; or 53 degrees for an elevation of three 
*s, making the mean temperature of January in lat, 40° at 
the height of three miles —21°. In order however that we may 
hot be Suspected of exaggeration, we will assume the temperature 
to be that of zero. Now at zero of Fahrenheit, the elastic force 
of vapor of water is equal to ;85 inch of mercury, or less than 
one inch of water: that is, if air at the temperature of zero were 
were precipr- 
Now it not unfrequently happens in one of our winter storms, 
at over a circle of 500 ack in diameter, the average fall of 
for the Si : he 
. ‘4 simple reason that more water falls than was ever con- 
tained in that stratum; and moreover it is highly probable that 
this Upper stratum contains well nigh as much moisture at the 
Sonclusion of a great storm, as it did at the commencement. 
/ 
ar. are no’ 
‘Nery great clearness, ‘On page 807 he says, “the on 
20n-periodic oscillations is exterior to the continent, an Bil 
wolf oeFessive movement, In no case is it apparent that t mr 
_ pitds, or an inflection of the polar atmosphere southward.” Mr. 
a 
