Clouds high in Venus’ atmosphere reveal features on planet’s surface

Sci News reports scientific findings that ‘winds, the water content, and the cloud composition – are somehow connected to the properties of Venus’ surface itself’.

Using data from ESA’s Venus Express spacecraft, European planetary researchers have shown how weather patterns seen in Venus’ cloud layers are directly linked to the topography of the surface below.

Venus is famously hot. The average temperature on the Venusian surface is 864 degrees Fahrenheit (462 degrees Celsius).

The climate at the surface is oppressive; as well as being hot, the surface environment is dimly lit. Ground-level winds are slow, pushing their way across the planet at speeds of only 3.2 ft/sec (1 m/sec).

However, that is not what we see when we observe our sister planet from above. Instead, we spy a smooth, bright covering of cloud.

This cloud forms a 12-mile (20 km) thick layer that sits 31-43 miles (50 – 70 km) above the surface and is far colder than below, with typical temperatures of about minus 94 degrees Fahrenheit (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.

While these clouds have traditionally blocked our view of Venus’ surface, meaning we can only peer beneath using radar or infrared light, they may actually hold the key to exploring some of Venus’ secrets.

Researchers suspected the weather patterns rippling across the cloud-tops to be influenced by the topography of the terrain below. They have found hints of this in the past, but did not have a complete picture of how this may work – until now.

Using Venus Express observations, a team of scientists from Europe has now greatly improved our climate map of Venus by exploring three aspects of the planet’s cloudy weather: (i) how quickly winds on Venus circulate; (ii) how much water is locked up within the clouds; and (iii) how bright these clouds are across the spectrum.

“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 team leader Dr. Jean-Loup Bertaux, from the Laboratoire Atmosphères, Milieux, Observations Spatiales in France.

“We used observations from Venus Express spanning a period of six years, from 2006 to 2012, which allowed us to study the planet’s longer-term weather patterns.”

The team studied Venus’ cloud-tops in the infrared part of the spectrum, allowing them to pick up on the absorption of sunlight by water vapor and detect how much was present in each location at cloud-top level (43 miles altitude).

They found one particular area of cloud, near Venus’ equator, to be hoarding more water vapor than its surroundings.
This region was located just above a 2.8-mile (4.5 km) altitude 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 the team to nickname this feature the ‘Fountain of Aphrodite.’
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The report goes on to consider the possible effects of gravity waves [graphic included]:
“When winds push their way slowly across the mountainous slopes on the surface they generate something known as atmospheric gravity waves.”

Full report: Clouds High in Venus’ Atmosphere Reveal Features on Planet’s Surface | Planetary Science | Sci-News.com