A curious cold layer in the atmosphere of Venus

October 1, 2012, European Space Agency

This image of the Venus southern hemisphere illustrates the terminator – the transitional region between the dayside (left) and nightside of the planet (right). The south pole is near the terminator, just above the centre of the image. The complex atmosphere that surrounds the planet is also clearly visible. The image was taken at ultraviolet wavelengths by the Venus Monitoring Camera (VMC) on ESA’s Venus Express spacecraft on 15 May 2006, when the spacecraft was flying at about 66 500 km distance from the planet. Credits: ESA/MPS, Katlenburg-Lindau, Germany
(Phys.org)—Venus Express has spied a surprisingly cold region high in the planet's atmosphere that may be frigid enough for carbon dioxide to freeze out as ice or snow.

The is well known for its thick, carbon dioxide atmosphere and oven-hot surface, and as a result is often portrayed as Earth's inhospitable evil twin.

But in a new analysis based on five years of observations using ESA's Venus Express, scientists have uncovered a very chilly layer at temperatures of around –175ºC in the atmosphere 125 km above the planet's surface.

The curious cold layer is far frostier than any part of Earth's atmosphere, for example, despite Venus being much closer to the Sun.

The discovery was made by watching as light from the Sun filtered through the atmosphere to reveal the concentration of molecules at various altitudes along the terminator – the dividing line between the day and night sides of the planet.

The temperature profile along the terminator for altitudes of 70–160 km above the surface of Venus. The values were derived from the volume density of carbon dioxide molecules measured during solar occultation experiments by Venus Express’ SOIR instrument. The graphic provides the average range of values calculated from 59 measurements taken along the terminator from 88ºN to 77ºS, during different orbits between 2006 and 2011. The new report finds a prominent cold layer at 125 km sandwiched between two comparatively warmer layers at around 100 km and 140 km. At some locations, the temperatures occasionally dip below the freezing temperature of carbon dioxide, which suggests that carbon dioxide ice or snow could exist at these altitudes. Credits: ESA/AOES–A.V. Bernus

Armed with information about the concentration of carbon dioxide and combined with data on at each height, scientists could then calculate the corresponding temperatures.

"Since the temperature at some heights dips below the freezing temperature of carbon dioxide, we suspect that carbon dioxide ice might form there," says Arnaud Mahieux of the Belgian Institute for Space Aeronomy and lead author of the paper reporting the results in the .

Clouds of small carbon dioxide ice or snow particles should be very reflective, perhaps leading to brighter than normal sunlight layers in the atmosphere.

"However, although Venus Express indeed occasionally observes very bright regions in the Venusian that could be explained by ice, they could also be caused by other atmospheric disturbances, so we need to be cautious," says Dr Mahieux.

The study also found that the cold layer at the terminator is sandwiched between two comparatively warmer layers.

"The temperature profiles on the hot dayside and cool night side at altitudes above 120 km are extremely different, so at the terminator we are in a regime of transition with effects coming from both sides.

"The night side may be playing a greater role at one given altitude and the dayside might be playing a larger role at other altitudes."

Similar temperature profiles along the terminator have been derived from other Venus Express datasets, including measurements taken during the transit of Venus earlier this year.

Models are able to predict the observed profiles, but further confirmation will be provided by examining the role played by other atmospheric species, such as carbon monoxide, nitrogen and oxygen, which are more dominant than at high altitudes.

"The finding is very new and we still need to think about and understand what the implications will be," says Håkan Svedhem, ESA's Venus Express project scientist.

"But it is special, as we do not see a similar temperature profile along the terminator in the atmospheres of Earth or Mars, which have different chemical compositions and conditions."

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1.7 / 5 (22) Oct 01, 2012
But how can Venus be cooling ask the denialists when the earth is Warming due to SunshineHours?

No wait. They ask, if the earth is cooling due to a decrease of sunshine hours over Switzerland how can that be causing the cooling of Venus?

No wait. They ask, if he Earth is warming due the the cooling of Alaska and the North pole how is the urban heat island effect cooling Venus?

No wait. They ask, if Venus is cooling due to changes on the sun, how is Mars warming?

No wait. They ask, if the rain in Spain falls mainly in the plane then can't a fleet of aircraft flying over America's forming desert bring needed moisture?

No wait. They ask, how could Christ be a socialist when every Sunday Morning, God Needs Money?
3.8 / 5 (6) Oct 01, 2012
Reading the whole article was to difficult I see? Show where it states that Venus is cooling. If you cannot, go spam some other site with your trollments and never come back.
1.3 / 5 (13) Oct 01, 2012
Planetary scientists decided in the 1970's to assume that Venus is in thermal equilibrium, even though four separate missions to descend into its atmosphere reported back that the heat of Venus was originating from its surface. The data was "normalized" in order to conform to the conventional view for Venus' formation, as part of an effort to discredit the threat of Immanuel Velikovsky's catastrophist notions.

Youtube "charles ginenthal venus" or Google "ted holden venus thermal equilibrium" for more details.

This turns out to be a very significant and controversial decision because, as David Talbott argues and Immanuel Velikovsky previously argued, the numerous concordant creation stories of the world cited Venus' arrival as a new planet with a cometary appearance within human historical times.
1.7 / 5 (6) Oct 02, 2012
The phrase "snowball's chance in hell" (literally) comes to mind when discussing the possibility of ice on Venus.
1.9 / 5 (9) Oct 02, 2012
Reading the whole article was to difficult I see? Show where it states that Venus is cooling. If you cannot, go spam some other site with your trollments and never come back.

You should have READ his comment. He was being extremely sarcastic, including his question how can Venus be cooling. He was doing his version of pulling facts out of his anus as global warming denialists are wont to do.
not rated yet Oct 02, 2012
Youtube "charles ginenthal venus" or Google "ted holden venus thermal equilibrium" for more details.

I don't do you-tube. Give me links that give me assurance the content has endured critical review. Otherwise, it's just crank science.
1 / 5 (1) Oct 05, 2012
All planets are cooling. Even venus... just.. very, very slowly. Magma temps at 1000 C or more. If venus' surface is 462 C, and its interior is a similar temp to earth, it's interior is hotter than its surface, so, it's still cooling.

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