zones the annual range is less than 10 deg.. In
the south temperate zone there are no extreme ranges, the maxima,
slightly over 30 deg., being near the margin of the zone in the interior
of South America, South Africa and Australia. In these same localities
the diurnal ranges rival those of the north temperate zone.

The north-eastern Atlantic and north-western Europe are about 35 deg.
too warm for their latitude in January, while north-eastern Siberia is
30 deg. too cold. The lands north of Hudson Bay are 25 deg. too cold,
and the waters of the Alaskan Bay 20 deg. too warm. In July, and in the
southern hemisphere, the anomalies are small. The lands which are the
centre of civilization in Europe average too warm for their latitudes.
The diurnal variability of temperature is greater in the north temperate
zone than elsewhere in the world, and the same month may differ greatly
in its character in different years. The annual temperature curve has
one maximum and one minimum. In the continental type the times of
maximum and minimum are about one month behind the dates of maximum and
minimum insolation. In the marine type the retardation may amount to
nearly two months. Coasts and islands have a tendency to a cool spring
and warm autumn; continents, to similar temperatures in both spring and
fall.

_Pressure and Winds._--The prevailing winds are the "westerlies," which
are much less regular than the trades. They vary greatly in velocity in
different regions and in different seasons, and are stronger in winter
than in summer. They are much interfered with, especially in the higher
northern latitudes, by seasonal changes of temperature and pressure over
the continents, whereby the latter establish, more or less successfully,
a system of obliquely outflowing winds in winter and of obliquely
inflowing winds in summer. In summer, when the lands have low pressure,
the northern oceans are dominated by great oval areas of high pressure,
with outflowing spiral eddies, while in winter, when the northern lands
have high pressure, the northern portions of the oceans develop cyclonic
systems of inflowing winds over their warm waters. All these great
continental and oceanic systems of spiralling winds are important
climatic controls.

The westerlies are also much confused and interrupted by storms, whence
their designation of _stormy westerlies_. So common are such
interruptions that the prevailing westerly wind direction is often
dif