Islands or high land, elevated above the surroundings and interrupting the air stream, can produce “tails” as well as “wakes.” Dek Island in Lake Tana in Ethiopia, the source of the Blue Nile, has frequently been observed by shuttle astronauts to have a well-developed cloud tail. This is created when the land mass disrupts the air flow, creating downwind turbulence that promotes condensation. The lake stands at 6000 feet above sea level.

STS 51-I, August-September 1985. Picture #27-38-003.

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