PMCs usually only appear near the poles, but during the past few decades they have appeared as far south as the American states of Colorado and Virginia. The clouds also have become brighter and thicker. Scientists think the changes are related to long-term climate change, perhaps from increasing water vapor content in the upper atmosphere.
The sunset shot (top) shows the PMCs only as a thin bright line, far above the lowest weather layer of the atmosphere (the troposphere). Looking away from the setting sun in the second image, the PMCs make a spectacular display. They are extensive enough to give a sense of disappearing into the distance, and thick enough to reveal fine details. Some astronauts have called PMCs “one of the most beautiful things you can see from orbit.”
Related Images
- NASA Earth Observatory (2013, January 21) Polar Mesospheric Clouds, South Pacific Ocean.
- NASA Earth Observatory (2012, June 25) Polar Mesospheric Clouds, Northern Hemisphere.
Astronaut photographs ISS040-E-87315 and ISS040-E-87351
was acquired on August 1, 2014, with a Nikon D3S digital camera using
an 85 millimeter lens, and is provided by the ISS Crew Earth
Observations Facility and the Earth Science and Remote Sensing Unit,
Johnson Space Center. The image was taken by the Expedition 40 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab
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. Caption by M. Justin Wilkinson, Jacobs at NASA-JSC.
- Instrument(s):
- ISS - Digital Camera - NASA
