Particles from a large dust storm in in the vicinity of the Egyptian-Sudanese border blow out over the Red Sea in this true-color image taken by the Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the NOAA/NASA Suomi NPP satellite yesterday, July 5, 2017.
Dust storms are caused by strong winds passing over the loose particles of sandy soils, causing them move over the ground and fracture, freeing smaller particles — i.e., the dust — that become airborne and transported by the wind. Scientists estimate that, on average, about 20 Tg of dust are suspended in the atmosphere at any given time and, about half of it is thought to originates in North Africa, due to both the abundance of dust sources there and the region’s position under the subtropical jet stream, which carries dust around the world. The rest is said to come from just a handful of other well-known dust-producing regions, including northwestern China’s Taklimakan Desert, parts of Arabia, Iran, the shore of the Caspian Sea, the Lake Eyre Basin in Australia, and the area around Utah’s Great Salt Lake.
Although true-color images like this may appear to be photographs of Earth, they aren’t. They are created by combining data from the three color channels on the VIIRS instrument sensitive to the red, green and blue (or RGB) wavelengths of light into one composite image. In addition, data from several other channels are often also included to cancel out or correct atmospheric interference that may blur parts of the image.
