n minimum temperatures of about, and
somewhat below, freezing occur in the northern portion of the district,
and in the more continental localities minima a good deal lower have
been observed. Mean maximum temperatures of about 95 deg. occur in
northern Italy, and of still higher degrees in the southern portions.
Somewhat similar conditions obtain in the sub-tropical district of North
America. Under the control of passing cyclonic storm areas, hot or cold
winds, which often owe some of their special characteristics to the
topography, bring into the sub-tropical belts, from higher or lower
latitudes, unseasonably high or low temperatures. These winds have been
given special names (mistral, sirocco, bora, &c.).

These belts are among the least cloudy districts in the world. The
accompanying curve, giving an average for ten stations, shows the small
annual amount of cloud, the winter maximum and the marked summer
minimum, in a typical sub-tropical climate (fig. 10). The winter rains
do not bring continuously overcast skies, and a summer month with a mean
cloudiness of 10% is not exceptional in the drier parts of the
sub-tropics.

[Illustration: FIG. 10.--Annual March of Cloudiness in a Sub-tropical
Climate (Eastern Mediterranean).]

With prevailing fair skies, even temperatures, and moderate rainfall,
the sub-tropical belts possess many climatic advantages which fit them
for health resorts. The long list of well-known resorts on the
Mediterranean coast, and the shorter list for California, bear witness
to this fact.

_North Temperate Zone: West Coasts._--Marine climatic types are carried
by the prevailing westerlies on to the western coasts of the continents,
giving them mild winters and cool summers, abundant rainfall, and a high
degree of cloudiness and relative humidity. North-western Europe is
particularly favoured because of the remarkably high temperatures of the
North Atlantic Ocean. January means of 40 deg. to 50 deg. in the British
Isles and on the northern French coast occur in the same latitudes as
those of 0 deg. and 10 deg. in the far interior of Asia. In July means
60 deg. to 70 deg. in the former contrast with 70 deg. to 80 deg. in the
latter districts. The conditions are somewhat similar in North America.
Along the western coasts of North America and of Europe the mean annual
ranges are under 25 deg.--actually no greater than some of those within
the tropics. Irregular cyclonic temperature changes ar