40 DR. NILS EKHOLM ON THE METEOROLOGICAL _—[ Feb.. 1902, 
winter, an increase of the oceanic influence on the European 
weather will tend to increase also the probability of an ice-age, 
under the supposition, of course, that the above-named general 
lowering of the mean temperature of the earth’s surface has taken 
place. In any case the influence of the winds alone will be but 
feeble, as the summer-temperature is only slightly influenced b 
them. | 
Still feebler, and indeed quite insensible, would be the influence 
of a glaciation of Europe on the climate of North America. For the 
influence of an ocean on the climate of the continent on its western 
side is in every case very small in our latitudes, as the general air- 
currents come from the west. Moreover, the cold Labrador current 
flowing past the American coast would prevent the Gulf-Stream 
from warming this coast, even if north-easterly winds were so 
common in the Northern Atlantic that they could deviate the Gulf- 
Stream so that it should flow from east to west. This deviation 
is, however, impossible, as the general direction of winds and 
ocean-currents is determined by the rotation of the earth, and by . 
the decrease of temperature from the Equator to the Poles. 
It must be borne in mind that the general atmospheric 
and oceanic circulation depends primarily on the state 
of the earth’s surface as a whole, and that the influence 
ofthe hot zoneis preponderating. In fact, let the Northern 
Hemisphere be divided into three zones, the first from the Equator 
to 40° lat. N., the second from 40° to 70° lat. N., and the third 
from 70° lat. N. to the Pole; and let us calculate the areas of those 
zones and the quantities of heat received by them from the sun, in 
percentages of that of the whole hemisphere. We find 
Quantity of heat 
Zone. Area. received in a year. 
per cent, per cent. 
O° 0-402, | ccusteeuscrnase 4s 64 73 
AD? fo 70? N.,.. cecrnsteneeu cane 30 24 
TOP. toQ0? Ni. ce oes 6 3 
Thus the first zone receives nearly three quarters of the whole 
heat, the second scarcely one quarter, and the third or Polar zone 
only 3 per cent. The difference of area is not quite so great, but 
it is still considerable. Hence we conclude that the first zone must 
play the principal part in all great and secular climatic changes. 
Now, the area of the Northern Hemisphere covered by a 
permanent ice-sheet during the Great Ice-Age was only 
about 9 or 10 per cent. of the area of the hemisphere; 
and therefore its influence on the general atmospheric 
circulation could not be very marked. 
Furthermore, the positions and movements of anticyclones are 
not generally determined by the temperature of the ground in 
our latitudes. In most cases they seem to be eddies formed by the 
great circulation going on between the tropical and temperate zones, 
and sometimes they persist during several weeks over Europe or 
North America in a hot summer month. As a rule, the great 
