From the above a simple climatic zonation can be derived. There is a nar-
row strip of a typical Mediterranean climate with rather cool, wet winters and
dry, hot summers in the north. The remaining parts of the country – with
the exception of Sinai – have a fully arid hot subtropical desert climate. A
decisive factor for Egypt’s climate is the location of the country between
two great climatic regimes, the zone of the westerlies to the north, which in
winter allow wet Atlantic air masses to enter the Mediterranean low-pressure
area, and the high-pressure area of the horse latitudes to the south, which is
responsible for the desert belt from the Atlantic coast of West Africa across
Egypt and Arabia to Central Asia. Owing to a northward shift of the high-
pressure area in summer, Egypt’s climate is hot and lacks rainfall during that
season. When the high-pressure area moves southward again, owing to the
changed position of the sun in winter, Atlantic cyclones enter the area of the
Mediterranean and cause rainfall there.
The winds prevailing in Egypt are the north-eastern trade winds. In winter
they are interrupted by WNW winds from the Atlantic. In spring and in early
summer there are spells of hot, dry dust storms called khamaseen, since they
usually occur during the fifty (khamseen) days between Easter and Whitsuntide,
according to the Coptic calendar.