'IRAQ AND THE PERSIAN GULF' [‎124r] (252/862)

CLIMATE
167
every day in July and August, but the nights are comparatively cool
(mean daily minimum July 78° F.). The inhabitants therefore build
their better houses with an underground room (sirdab) where they
pass the heat of the day, but sleep at night on the flat roofs to
benefit by the fall in temperature (p. 349). Generally in the extreme
south the day temperatures are not quite so high, for the wind
may be cooled by the marshes, but the night temperatures are
often higher than in the north. Away from the towns there is
less relief from the heat; the scanty vegetation is burnt up by
the fierce sun, the sky pales from the dust in the atmosphere, and
mirage after 9 a.m. reduces visibility to a few hundred yards.
During the War of 1914-1918 some relief was obtained from the
heat by excavating pits beneath the tents, thus improvising a kind
of sirdab ; but these, like the trenches, were apt to harbour sandflies;
dark glasses, spine-pads, and even umbrellas helped to mitigate the
heat and glare, especially among those whose work was on the rivers.
Autumn is more marked in the north than south of Baghdad, but it
is everywhere very short. Winter comes suddenly and lasts from
November to April. North-west winds still prevail, but they are
weaker and are frequently interrupted by depressions from the
Mediterranean; with the south-east winds (Sharqi) which blow in
front of them come cloudy skies, rain, and cold. In lower Mesopo
tamia rainfall is about 5 inches on the average, but some winters are
much wetter than others. The rain is often heavy and unpleasant
while it lasts, and it quickly turns the deltaic alluvium into a morass of
sticky mud, in which all forms of transport become bogged (photo. 70).
The temperature falls greatly during the night, so that the relative
humidity rises. Frosts may occur in any of the five months November
to March anywhere in Iraq, except perhaps in parts of the extreme
south, where Shuaiba has only once recorded 32 0 in November; these
frosts coming after rain accompany the cold north-west winds which
follow in the wake of the depression. Snow has been known to lie
in the plains for several days. The winter may be fairly severe in the
north, and at Mosul the temperature on one occasion remained below
freezing-point for nine days. Every year snow covers the Persian
and Kurdish mountains, where the total precipitation exceeds 40
inches (photo. 71).
Spring, which occurs during April, is almost as fleeting as autumn;
it lasts for less than a month and is noticeable for a slight rainfall,
generally accompanied by thunder, and for a change in the desert
colouring. For a few days, occasionally for a few weeks, the desert is