"العراق والخليج الفارسي" [و‎‎١‎٢‎٥] (٨٦٢/٢٥٤)

CLIMATE 169
1-i SWMISA
/Mjai
k
DmiYA
HINAIOI
imwi
flUTSA
flushed with a faint tinge of green, marking a change from the brown
of winter to the dusty drab of summer.
The notes that follow are based mainly on the observations of the
few stations given below. The Tables given in Appendix B are
mostly from official manuscript records. They do not yet cover a
period long enough to be conclusive on many points, and there are
only rainfall records in the mountains. Since 1938 a new station at
Basra Airport (Maqil) has been set up. Figures are given for 1938
and 1939 in the Statistical Abstract ig40, but are only occasionally
referred to here, as the information is incomplete and not always
accurate.
Region
Station
Alt. in feet
Years of observation
Lower Delta
Shuaiba 1 (near Basra)
60
9-18 (1922-1939)
Mesopotamian
Diwaniya (Euphrates)
70
12 (1928-1939)
plains
Hinaidi (Baghdad)
no
16 (1922-1937)
Assyrian plains
Mosul
73 °
6-15 (1922-1936)
Western Desert
Rutba
2,020
10 (1928-1937)
Pressure and Winds (figs. 44, 45 ; Table I)
In winter the high-pressure system of central Asia extends south
wards into Persia, and the gradient is south-westwards to Iraq. This
guides a general flow of air from the north-east towards Arabia, thus
intensifying the theoretical trade-wind circulation; but the gradient
is broken by the Persian Gulf, and air is drawn from the moving mass
down the Mesopotamian trough, thus causing a cold north-westerly
wind in winter over most of the country. In the Syrian desert south
west of the Euphrates cold air from local high pressures over western
Arabia contribute a predominant westerly wind. None of these winds
are constant or uniform, being frequently interrupted by depressions
moving eastwards from the Mediterranean, particularly in December,
January, and February. The warm winds in front of the depressions
are south-easterly (Sharqi) and they break up the normal winter
circulation. The north-west winds in rear of the depressions are
cold and very dry, and they bring clear skies and lower temperatures;
they are occasionally strong, but more usually very light. In the
gulf area the Sharqi, in places known as the Kaus, is sometimes
followed by a strong south-westerly gale (Suahili) which lasts for a
few hours and is dangerous to small craft.
1 The meteorological station is always spelt Shaiba. The spelling used here
(Shuaiba) is that shown on the quarter-inch maps of Iraq and has been used
throughout this volume.