Shamal (wind)

A shamal (Arabic: شمال‎‎, 'north') is a northwesterly wind blowing over Iraq and the Persian Gulf states (including Saudi Arabia and Kuwait), often strong during the day, but decreasing at night. This weather effect occurs anywhere from once to several times a year, mostly in summer but sometimes in winter. The resulting wind typically creates large sandstorms that impact Iraq, most sand having been picked up from Jordan and Syria.

Shamals result from strong northwest winds that are funneled into the Persian Gulf by the mountains of Turkey and Iraq to the northeast and the high plains of Saudi Arabia to the southwest. The winds most commonly are strongest in the Spring to Summer and hence the Shamal events are as well, although they can occur at any time of year. During that time of year the polar jet stream to the north moves southward to become close to the subtropical jet to the south. The proximity of the two jet streams promotes the formation of strong but often dry cold fronts which create the Shamal. The strong winds of the Shamal form in front of and behind the front. Iraq typically experiences strong wind-driven dust 20 to 50 days per year.

According to folklore, the first major shamal occurring around May 25 is known as the Al-Haffar, or driller, since it drills huge depressions in desert sand dunes. The second, arriving in early June, coincides with the dawn star, Thorayya (Pleiades), and is therefore named Barih Thorayya. During this event, which is more violent than the others, fishermen usually remain in port because ancient folklore tells them that this wind devours ships. Near the end of June, the last shamal arrives, known as the Al-Dabaran, or the follower. It is violent and continues for several days. Local residents keep doors and windows firmly shut as this shamal includes an all-penetrating fine dust which gets into everything.

When a passing storm with a strong cold front passes over the mountains of Turkey, the leading edge of a mass of relatively cooler air kicks up dust and sand, sending it aloft. Temperatures at lower elevations still hover above 105 °Fahrenheit (42 °Celsius) during these events. In Iran, where winter storms can bring heavy snow to the terrain, a layer of dust can settle onto the snowpack.

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Wikipedia