266 J, Crol— Geological Climatology. 
atmosphere sufficiently diminished, perpetual snow would 
cover our globe down to the sea shore. It is true that the air 
is warmer at the lower than at the higher levels, and by con- 
tact with the snow must tend to melt it more at the former 
than at the latter position. But we must remember that the | 
air is warmer mainly in consequence of the influence of 
aqueous vapor, and that were the quantity of vapor reduced 
to the amount in question, the difference of temperature at 
2,000 or 3,000 feet below that of the opposite or dry side. 
But this is owing to the fact that it is on the moist side 
that by far the greatest amount of snow is precipitated. The 
moist winds of the southwest monsoon deposit their snow 
almost wholly on the southern side of the Himalayas, and the 
southeast trades on the east side of the Andes. Were the 
ine. 
The annual precipitation on Greenland, as we have seen, 18 
very small; scarcely one-half that of the dryest parts of Great 
Britain. This region is covered with snow and ice, not 
because the quantity of snow falling on it is great, but 
because the quantity melted is small ; and the reason why the 
snow does not melt is not that the amount of heat received 
during the year is unequal to the work of melting the ice, but 
that, mainly through the dryness of the air, the snow 1s pre- 
vented from rising to the melting point. The very cause 
which prevents a heavy snowfall protects the little which does 
fall from disa ing. The same remarks apply to the ant- 
arctic regions. 
In South Georgia and Fuegia, where clouds and dense fogs 
prevail during nearly the whole year, the permanent snow and 
