Several planes and a terminal building have been damaged at Blaise Diagne International Airport in Dakar, Senegal, and local communities have recorded a number of livestock deaths after the city was hit by a dust storm this week, bringing with it winds of up to 90 kilometres per hour, and near zero visibility.
The approximate location of the June 2018 Dakar duststorm. Google Maps.
The dust storm is thought to have been caused by a weather phenomenon called a haboob, which occurs when thunderstorms, or forming thunderstorms, collapse, causing a rapid downdraught of air. Thunderstorms are caused by heating of the land or water surface by the sun, causing air to expand, and thus rise, this causes more air to be drawn in to fill the gap, which is in turn heated and rises, repeating the process and creating a cycle. However under some circumstances the air at the top of this column does not move away, but forms an air package in the upper atmosphere which cools in place, then collapses back down to the ground creating a cool downdraught. As this typically happens in desert areas, it can stir up a great deal of dry sediment when it reaches the ground, creating potentially harmful dust and sand storms. This process is generally associated with the interior of deserts such as the Sahara, but in this case appears to have hit the Senegalese coastal city as a storm formed around the onset of the local rainy season, possibly due to exceptionally hot conditions in the area this year, which could have caused updraughts over a wider area, preventing air from escaping from the top of the storm system.
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