Madeira's vortex street

Madeira is a Portuguese island in the Atlantic, north of the Canaries, in the path of the north-east trade wind.

What the satellite saw

Large cloud swirls trailing south-west from Madeira, the Canary Islands lower right
Madeira, 9 July 2020: two big eddies of opposite spin behind the island, the Canaries below. NASA Earth Observatory image by Joshua Stevens, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview ("Cloudy Curls"). Public domain.
The wake behind Madeira as Wind Tunnel draws it, the NASA photo of the real one laid over the lower right corner
Madeira in Wind Tunnel with Satellite photo on: the simulation, made in your browser, with NASA's photo in the corner.

NASA's Terra satellite photographed it with MODIS on 9 July 2020 (Earth Observatory, "Cloudy Curls"). Two big eddies of opposite spin trail to the south-west, the Canary Islands in the lower right.

NASA's account: the air, and the clouds moving with it, blows around the island instead of over it. Behind it the flow slows, and the sheets of fast air passing slow air roll up into eddies that leave the two sides in turn.

Why Madeira

Height. Pico Ruivo rises to 1,861 m.

The trade wind. Steady from the north-east through the summer.

A long island across the wind. Its width sets how big the eddies are and how far apart they sit.

Make it in Wind Tunnel

  1. Open the link below, or press Madeira under Island: the wind starts from 30°, north-north-east.
  2. Press Cloud under Look and Satellite under Colour: white cloud on a blue-grey sea, as the photo sees it.
  3. Turn on Satellite photo under Island to lay this photo over the corner of the frame, beside the flow.
  4. Choose 4K and 20 seconds under Save, and press MP4 once the street has formed.

Open Madeira in Wind Tunnel