A sandstorm rolled into Phoenix on Thursday evening, downing power lines, stalling traffic, and delaying flights for the third time this summer. Video footage from local news stations shows a brown cloud hundreds of feet high and with winds of up to 60 miles per hour advancing on the city. Sandstorms, known also haboobs in Arabic, form when thunderclouds burst in arid regions, sending high winds into the desert floor and kicking up sand. The previous storms, both in July, reached thousands of feet in height and were responsible for similar disruptions. Haboobs happen frequently in north Africa's Sahara Desert, but can occur in any arid region and are not uncommon in the Middle East and the American Southwest. Phoenix often sees two to three storms in a summer.
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