Phoenix hit by second dust storm
19 July 2011 Last updated at 14:05 BST
A giant wall of dust rolled through the Phoenix area on Monday, turning the sky brown and delaying some airline flights.
The dust wall was about 1,000m high and created winds of 25 to 30 mph, with gusts of up to 40 mph, according to a meteorologist with the National Weather Service.
Another giant dust storm in Arizona caught worldwide attention on 5 July. Both are part of the Arizona monsoon season, which typically starts in mid-June and lasts until the end of September.