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Please, try and blame this one on global warming.

The Earth’s upper atmosphere is rapidly cooling.  It is rapidly cooling because the sun is “inactive”.

“…When the sun is relatively inactive — as it has been in recent years — the outermost layer of Earth’s atmosphere cools dramatically, new observations find.

The results could help scientists better understand the swelling and shrinking of our planet’s atmosphere, a phenomenon that affects the orbits of satellites and space junk.

The data, from NASA’s TIMED mission, show that Earth’s thermosphere (the layer above 62 miles or 100 km above the Earth’s surface) “responds quite dramatically to the effects of the 11-year solar cycle,” Stan Solomon of the National Center for Atmospheric Research in Boulder, Colo., said here this week at the annual meeting of the American Geophysical Union.

Knowing just how the energy flowing out from the sun naturally impacts the state of the thermosphere also will help scientists test predictions that man’s emissions of carbon dioxide should cool this layer. (While that may seem to contradict the idea of global warming, it has long been known that carbon dioxide causes warming in the lowest part of the atmosphere and cooling in the upper layers of the atmosphere.)…”The sun is in a very unusual period,” said Marty Mlynczak, a TIMED team member at NASA Langley in Virginia. “The Earth’s thermosphere is responding remarkably – up to an order of magnitude decrease in infrared emission/radiative cooling by some molecules.”

Less radiation in both directions means that this layer of the atmosphere also cools substantially. In fact, the thermosphere has cooled by a factor of 10 since the last solar maximum in early 2002.

“I certainly didn’t expect to see this eight years ago,” Mlynczak said.

The exact temperature of the thermosphere can vary substantially, but the average temperature above 180 miles (300 km) is about 800 degrees Fahrenheit (427 degrees Celsius) at solar minimum and 1,700 degrees Fahrenheit (927 degrees Celsius) at solar maximum. (Though these temperatures sound hot, you would not actually feel warm in the thermosphere, because the molecules in that layer are too far apart.)

The temperature at this extreme solar minimum is likely a few degrees colder than in an average minimum, but that small change can cause a large change in the density of the layer….”

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