Into the summer months, a prevailing northwesterly wind - known locally as the Shamal - kicks up the fine desert sand and the silt along the Tigris and Euphrates river basins, creating swirling dust storms. From the south, the Sharqi winds can gust up to 50 mph. These winds can create sandstorms that might clog military machinery and reduce visibility for troops. Wind conditions could also come into play during a chemical weapons attack, explains retired Marine and military historian Col. Joseph Alexander.