August 18, 2021 - Dust off Socotra Island
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Dust off Socotra Island
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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.
Image Facts
Satellite: Terra
Date Acquired: 8/17/2021
Resolutions: 1km (1.8 MB), 500m (5.1 MB), 250m (2.9 MB)
Bands Used: 1,4,3
Image Credit: MODIS Land Rapid Response Team, NASA GSFC
https://modis.gsfc.nasa.gov/gallery/individual.php?db_date=2021-08-18
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