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Sand Dunes, Idaho

Credits
NASA (Jesse Allen, Robert Simmon); Link: http://earthobservatory.nasa.gov

Along highway 20 from Idaho Falls heading toward Yellowstone National Park, green and golden fields dominate the fertile plain of the Snake River. The circular areas indicate extensively irrigated farmland. The white dunes developed towards the end of the last ice age approximately 10 000 years ago when the global climate started to become warmer and drier. Lakes and rivers dried up leaving fine sand behind. Continuous winds from the south west blew the sand in northeasterly direction, passing lava fields which are quite dark in the picture.

 

Penguin Traces

Credits
NASA/GSFC; Link: http://earthobservatory.nasa.gov

The Antarctica emperor penguins are endangered. Due to the global temperature increase, the ice in the south will melt quickly and the birds will lose their natural habitat. Scientists use satellite images in order to investigate the number of penguins in the Antarctic. Since the penguins are hard to detect due to their black and white feathering, scientists look for their excrements. In the middle of the picture, you can see brown lines that cannot originate from the ice and thus must be organic: This so-called seabird guano clearly indicates the presence of a penguin colony.

Lignite Surface Mines in Germany

Credits
NASA/GSFC; Link: http://visibleearth.nasa.gov

This image shows an area in North Rhine-Westphalia spanning 30x36 km. The numerous rectangular areas depict agricultural plains. Bright shades of green signal plant growth, dark shades of green stand for forests and shades of grey indicate bare ground. Settlements are characterised by the accumulation of blue and grey pixels connected by thin lines (streets). The three large areas standing out due to their bright white and dark blue colour are the three big lignite surface mines in Garzweiler, Hambach and Inden.

 

Glacier in Patagonia

Credits
NASA/GSFC; Link: http://visibleearth.nasa.gov

Patagonia is a mountainous region at the border between Chile and Argentina. You can see that the glacier (white) streaming from the mountains towards the foothills is interspersed with crevasses. The semicircular crest far left in the picture is pierced by three glacial rivers. The crest consists of coarse gravel, forming the terminal moraine for a long time, deposited by the ice tongue. Thus, the moraine marks the end of the glacier in former times and indicates a retreat of ice. In this false colour image, the vegetation is depicted in red.

 

Susitna Glacier in Alaska

Credits
NASA/GSFC (Jesse Allen, Robert Simmon)

In this false colour image, the Susitna Glacier in Alaska seems like a river fed by its influent streams and flowing towards the valley. Due to the depiction in false colour, the vegetation in this picture is bright red, the pure surface of the ice is light blue and white, ice covered with sediment (medial and lateral moraines) is brown and water is dark blue. The dynamics of the glacier are most striking in the middle of the picture where you can see a tributary glacier pushing its ice masses sideways into the trunk glacier.

 

Location: Alaska