File:Dust off Socotra Island (MODIS 2021-08-18).jpg

English: Strong winds sent dust scurrying from the Horn of Africa northward over the Gulf of Aden on August 17, 2021. When NASA’s Terra satellite passed over the region on that date, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board acquired a true-color image of the sandy scene. Clouds and tan dust visible at the left (west) edge of the image lie on the eastern edge of a larger plume of airborne dust. In the east, two long, parallel streamers of dust flow off of Socotra Island, a rugged and dry island which sits at the entrance to the Gulf of Aden.

Part of the Republic of Yemen, the Island of Socotra (Soqotra) lies about 200 miles (320 km) south of the mainland. Tall mountains rise to about 5,000 feet (1,500 m) from near the center of the 80-mile-long island, creating steep topography that juts skyward abruptly from the surrounding waters. In the vernacular of fluid dynamics, such tall obstacles are called “bluff bodies”, and they basically stop the forward motion of moving fluid (or air), driving it sideways around the object. This creates turbulence on the lee side of the object, which can create a variety of wakes.

Although atmospheric wakes are invisible in clear air, dust-laden air often beautifully reveals the motion when viewed from space. In this case, a pulse of dust-laden air is pushing past the edges of Socotra Island, creating two dramatic tan plumes that brilliantly contrast with the blue water below. Where the wind speed drops and turbulence fades, the dust plumes widen until, near the coast of Oman, the dust becomes a tan cloud.