The long cold period this winter has led to the formation of a completely smooth, transparent sheet of ice on several Alpine lakes. The lakes then look black because you can see through the crystal-clear ice to the deep dark water below. You get an uncanny but fascinating feeling sliding around on this black ´ice´.
Seen from the air these sheets of black ice display wild erratic patterns as seen here in the Upper Engadin in Switzerland. The dark surface is interlaced with a fine mesh of stress cracks. Air bubbles which have risen from the bottom of the lake and frozen in the sheet of ice appear as large cloud-like structures. The two ice skaters in the top right of the photograph above give you an idea of the size.
The Silvaplana lake is 3.1 kilometres long, up to 1.4 kilometres wide with a maximum depth of 78 metres. It forms part of the Engadine lakeland near St. Moritz with the river Inn flowing through it.