Natural-colour image of the Omulyakhskaya and Khromskaya Bays, Russia. The land around the bays is dotted with thermokarst lakes, which result from <a href="//commons.wikimedia.org/wiki/Water" title="Water">water</a> released by thawing <a href="//commons.wikimedia.org/wiki/Category:Permafrost" title="Category:Permafrost">permafrost</a>. The water in a thermokarst lake doesn’t always stay put; these lakes can melt through the surrounding permafrost and drain into a nearby water body, especially if it sits at a slightly lower elevation. This appears to have occurred in multiple lakes between the bays shown above. (The compound lakes are identifiable by their uneven margins.) <a href="//commons.wikimedia.org/wiki/Category:Coastal_erosion" title="Category:Coastal erosion">Coastal erosion</a> and <a href="//commons.wikimedia.org/wiki/River" title="River">river</a> <a href="//commons.wikimedia.org/wiki/Category:Migration" title="Category:Migration">migration</a> also can deplete the lakes. Dark <a href="//commons.wikimedia.org/wiki/Brown" class="mw-redirect" title="Brown">brown</a> spots, especially numerous east of Khromskaya Bay, are probably locations of former thermokarst lakes.<p>Image captured by the Thematic Mapper on the Landsat 5 satellite. Landsat data provided by the United States Geological Survey.</p>
Jesse Allen and Robert Simmon
<a rel="nofollow" class="external text" href="http://earthobservatory.nasa.gov/IOTD/view.php?id=51712">NASA Earth Observatory</a>