A haboob, a type of sandstorm featuring a fast-moving wall of sand and dust, advances on a livestock market near Khartoum, Sudan. Relaticely common in the region, a haboob forms within minutes as huge downdrafts of air in stormclouds force dust and sand outwards. On a January afternoon, the wall of a haboob advances towards a livestock market in Omdurman, soon engulfing it in swirling brick-red grit..