ienced have been in the vicinity of 10 deg.,
and the minima of an ordinary antarctic winter go down to -40 deg. and
below, but so far no minima of the severest Siberian intensity have been
noted. The maxima have varied between 35 deg. and 50 deg.

The temperatures at the South Pole itself furnish an interesting subject
for speculation. It is likely that near the South Pole will prove to be
the coldest point on the earth's surface for the year, as the
distribution of insolation would imply, and as the conditions of land
and ice and snow there would suggest. The lowest winter and summer
temperatures in the southern hemisphere will almost certainly be found
in the immediate vicinity of the pole. It must not be supposed that the
isotherms in the antarctic region run parallel with the latitude lines.
They bend polewards and equatorwards at different meridians, although
much less so than in the Arctic.

The annual march of temperature in the north polar zone, for which we
have the best comparable data, is peculiar in having a much-retarded
minimum in February or even in March--the result of the long, cold
winter. The temperature rises rapidly towards summer, and reaches a
maximum in July. Autumn is warmer than spring.

The continents do not penetrate far enough into the arctic zone to
develop a pure continental climate in the highest latitudes.
Verkhoyansk, in lat. 67 deg. 6' N., furnishes an excellent example of an
exaggerated continental type for the margin of the zone, with an annual
range of 120 deg.. One-third as large a range is found on Novaya Zemlya.
Polar climate as a whole has large annual and small diurnal ranges, but
sudden changes of wind may cause marked irregular temperature changes
within twenty-four hours, especially in winter. The smaller ranges are
associated with greater cloudiness, and vice versa. The mean diurnal
variability is very small in summer, and reaches its maximum in winter,
about 7 deg. in February, according to Mohn.

_Pressure and Winds._--Owing to the more symmetrical distribution of
land and water in the southern than in the northern polar area, the
pressures and winds have a simpler arrangement in the former, and may be
first considered. The rapid southward decrease of pressure, which is so
marked a feature of the higher latitudes of the southern hemisphere on
the isobaric charts of the world, does not continue all the way to the
South Pole. Nor do the prevailing westerly winds, constit