Shamal (wind)
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A shamal is a summer northwesterly wind blowing over Iraq and the Persian Gulf, often strong during the day, but decreasing at night.[1] This weather effect occurs anywhere from once to several times a year. The resulting wind typically creates large sandstorms that impact Iraq, although most sand is picked up from Jordan and Syria.
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[edit] Synoptic setup
When a passing storm with a strong cold front passes over the mountains of Turkey and Kurdistan, 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.[2] In Iran, where winter storms can bring heavy snow to the terrain, a layer of dust can settle onto the snowpack.[3]
[edit] Climatology
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. 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.[4]
[edit] Rare winter cases
The places around the Middle East most likely to see the winter variety lie near Lavan Island, Halul Island, and Ras Rakan. They persist from 24 to 36 hours during the winter and occur as frequently as two to three times per month between December and February. A persistent three to five day event occurs only once or twice a winter, and is accompanied by very high winds and seas.[5]
[edit] Effects
Shamals normally last three to five days. Since the resultant dust and sandstorm is several thousand feet deep, travel by air and ground comes to a standstill. When they spread to nearby bodies of water, fishing and shipping become equally difficult. During these wind events, several Southwest Asia international airports have recorded winds as high as 49 mph (43 knots) which can drive dust over large distances downwind.[6]
[edit] Past example
A notable storm caused by a shamal covered Baghdad with sand on August 8, 2005, resulting in a closing of nearly all shops and public activity. The storm also overwhelmed Baghdad's Yarmuk Hospital, which treated more than a thousand people with respiratory distress.[7]
[edit] Trivia
A question about this wind showed up in the 2003 National Geographic Bee.[8]
[edit] See also
- Dust storm or Sandstorm
[edit] References
- ^ Golden Gate Weather Services. Names of Winds. Retrieved on 2006-12-09.
- ^ Weather Corner: Desert wind pattern in Iraq to shift in next two months. Retrieved on 2006-12-09.
- ^ NASA Earth Observatory. Natural Hazards >> Dust & Smoke >> Shamal Winds Drive Middle East Dust Storm. Retrieved on 2006-12-09.
- ^ DataDubai. Climate: March 16, 2006. Retrieved on 2006-12-09.
- ^ United States Navy. Appendix C: Wind Climatology of the Winter Shamal. Retrieved on 2006-12-09.
- ^ NOAA Magazine. DUST STORMS, SAND STORMS AND RELATED NOAA ACTIVITIES IN THE MIDDLE EAST. Retrieved on 2006-12-09.
- ^ NASA Earth Observatory. New Images: Iraq Dust Storm. Retrieved on 2006-12-09.
- ^ CNN. AMERICAN MORNING: Interview With National Geographic Bee Champion. Retrieved on 2006-12-09.
