Cold Atmosphere in Venus Can Convert Carbon Dioxide to Ice or Snow

Noted for being the brightest object in the sky besides the sun and moon, Venus is the only planet that is referred to Earth's Twin due to their similar size, mass, density, composition and gravity.

Venus is known to be covered with thick clouds that create a greenhouse effect making it a hot and inhospitable.

But recently Venus Express has detected a cold layer high in the planet's atmosphere that is so cold and frosty that it could convert carbon dioxide to freeze out as ice or snow.

Based on the five years of observation 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.

According to the scientist this cold layer is far frostier than any part of Earth's atmosphere.

By analyzing the sun that is being filtered through the atmosphere, they revealed the concentration of carbon dioxide gas molecules at various altitudes along the terminator that is the dividing line between the day and night sides of the planet.

"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.

The details of this finding were carried in the Journal of Geophysical Research.

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

They researchers also noticed that the cold layer at the terminator is clubbed 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."