Venus'' clouds may unveil underlying secrets

London

Venus' thick cloud layers may offer insight into the topography of the planet's surface below, rather than acting as a barrier to our observations, scientists have shown for the first time.

An extreme greenhouse effect on Venus heats its surface to temperatures as high as 450 degrees Celsius.

A 20-km-thick layer sits between 50 and 70 km above the surface of Venus and is far colder than below, with typical temperatures of about minus 70 degrees Celsius – similar to temperatures found at the cloud-tops of Earth.

The upper cloud layer also hosts more extreme weather, with winds that blow hundreds of times faster than those on the surface (and faster than Venus itself rotates, a phenomenon dubbed 'super-rotation').

While these clouds have traditionally blocked our view of Venus' surface, they may actually hold the key to exploring some of the planet's secrets, researchers said.

Scientists suspected the weather patterns rippling across the cloud-tops to be influenced by the topography of the terrain below.

Researchers using observations from European Space Agency (ESA)'s Venus Express satellite have now greatly improved our climate map of Venus by exploring three aspects of the planet's cloudy weather: how quickly winds on Venus circulate, how much water is locked up within the clouds, and how bright these clouds are across the spectrum (specifically in ultraviolet light).

"Our results showed that all of these aspects — the winds, the water content, and the cloud composition — are somehow connected to the properties of Venus' surface itself," said Jean-Loup Bertaux of LATMOS (Laboratoire Atmospheres, Milieux, Observations Spatiales) in France.

Although Venus is very dry by Earth standards, its atmosphere does contain some water in the form of vapour, particularly beneath its cloud layer

Researchers studied Venus' cloud-tops in the infrared part of the spectrum, allowing them to pick up on the absorption of sunlight by water vapour and detect how much was present in each location at cloud-top level (70 km altitude).

They found one particular area of cloud, near Venus' equator, to be hoarding more water vapour than its surroundings.

This 'damp' region was located just above a 4500 metre high mountain range named Aphrodite Terra.

This phenomenon appears to be caused by water-rich air from the lower atmosphere being forced upwards above the Aphrodite Terra mountains, leading researchers to nickname this feature the 'fountain of Aphrodite'.

"This 'fountain' was locked up within a swirl of clouds that were flowing downstream, moving from east to west across Venus," said Wojciech Markiewicz of the Max-Planck Institute in Germany. — PTI