Cape verde Islands
Our atmosphere is full of turbulent eddies, ranging from the well-known (extra-)tropical low-pressure areas down to the molecular scale, as was summarised in 1922 by L.F. Richardson in the rhyming verse “Big whirls have little whirls that feed on their velocity, and little whirls have lesser whirls and so on to viscosity”. Turbulent phenomena that are frequently observed by PROBA-V are von Kármán cloud vortices, which are flow disturbances in the wake of large objects, such as islands. When a prevailing wind encounters the islands, the flow is separated, which may result in a repeating vortex pattern that becomes visible by the presence of clouds. The image of 13 June 2014 shows a couple of von Kármán cloud vortices that have formed downstream of the northern Cape Verde Islands in a north-easterly flow. In the lower image part, the eastern Cape Verde islands are visible, with the volcanic island Fogo recognisable by a black stain.