Guadalupe Island's vortex street
Guadalupe is a volcanic island in the Pacific, about 240 km off Baja California, Mexico. In summer it sheds a vortex street into the clouds almost every day, and it is one of the streets satellites photograph most often.
What the satellite saw
NASA's Suomi NPP satellite photographed it with its VIIRS camera on 24 May 2017 (Earth Observatory, "Two Views of Von Kármán Vortices"). The island sits in a clear hole in the cloud deck; the eddies curl away to the south-east, one from each side in turn.
Why Guadalupe
Height. The island rises to about 1,300 m, far above the low cloud deck. The air cannot climb over it, so it goes around.
A lid. In summer a layer of warm, dry air lies over the cool sea, an inversion. The marine cloud is trapped under it, so the flow behaves almost like a flat sheet of fluid passing a post, which is what the tunnel computes.
A steady wind. The north-north-west wind down the coast of California blows for days without changing, long enough for a street hundreds of kilometres long to form.
Isolation. Nothing upwind disturbs the flow, so the street comes out clean.
Make it in Wind Tunnel
- Open the link below, or press Guadalupe under Island: the wind starts from 340°, north-north-west.
- Press Cloud under Look and Satellite under Colour: white cloud on a blue-grey sea, as the photo sees it.
- Turn on Satellite photo under Island to lay this photo over the corner of the frame, beside the flow.
- Choose 4K and 20 seconds under Save, and press MP4 once the street has formed.