Earth Observatory HomeNASAEarth Observatory HomeData and ImagesFeaturesNewsReferenceMissionsExperimentsSearch
NASA's Earth Observatory
 Earth Observatory Navigation Bar
  New Images

Sand Dunes in Har Nuur (Black Lake), Western Mongolia
Sand Dunes in Har Nuur (Black Lake), Western Mongolia Click here to view full image (321 kb)

Har Nuur (“Black Lake”) is located in western Mongolia’s Valley of Lakes, part of a system of closed basins stretching across central Asia. These basins are the remnants of larger paleolakes (paleo- means “ancient”) that began to shrink approximately five thousand years ago as regional climate became drier. Like other lakes in the region, Har Nuur relies on precipitation, growing in the spring and shrinking in the summer. This process of growth and shrinkage produces a variety of wetland habitats, as well as resting points for large numbers of migratory birds.

This oblique (looking at an angle) astronaut photograph captures the dynamic nature of the landscape of Har Nuur. The lake is encircled by sand dune fields that encroach on the lower slopes of the Tobhata Mountains to the west and south. Gaps in the mountains have been exploited by sand dunes moving eastward, indicating westerly winds. The most striking example is a series of dunes entering Har Nuur along its southwestern shoreline. Here, the dune forms reflect the channeling of winds through the break in the mountain ridgeline, leading to dune crests lying perpendicular to northwesterly winds. Another well-developed line of dunes appears between Har and Baga Lakes; while these dunes appear to cut across a lake surface, the dunes have in fact moved across a narrow stream channel.

Astronaut photograph ISS013-E-78506 was acquired September 7, 2006, with a Kodak 760C digital camera using a 400 mm lens, and is provided by the ISS Crew Earth Observations experiment and the Image Science & Analysis Group, Johnson Space Center. The International Space Station Program supports the laboratory to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth.

Recommend this Image to a Friend

Back to: Newsroom

Also see
Visible Earth

Latest Images
View Images Index

Sundarbans, Bangladesh
  Sundarbans, Bangladesh

  "Chemical Weather Forecasts:" Carbon-Containing Particles

Amazon River in the Atlantic Ocean
  Amazon River in the Atlantic Ocean

Subscribe to the Earth Observatory
About the Earth Observatory
Please send comments or questions to:
Responsible NASA Official: Dr. Michael D. King
NASA/GSFC Security and Privacy Statement

The above content is a copy of the original posting of this article as it appeared on
Contact information regarding its posting in this archive is below:
Send questions or comments about this web page to the NASA Responsible Official at
Curator: Earth Sciences Web Team
Notices: Web Accessibility and Policy Notices, NASA Web Privacy Policy