We have been looking closely at the clouds of Venus for almost 55 years, and we have finally now found a way to use them to learn about what lies beneath.
European scientists used data from ESA’s Venus Express spacecraft, which was de-orbited in 2015, and discovered a link between the Venusian weather patterns and what the surface below looks like.
In a paper, published in the Journal of Geophysical Research: Planets, the researchers discussed the wind speed and water content in the clouds above Aphrodite Terra, a 4,500-meter-high (2.8-mile-high) relief on the equator that's roughly the size of Africa. The team thinks that the height of the region is responsible for the different weather.
"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 lead author Jean-Loup Bertaux in a statement. "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."
While Venus is too hot and dry for liquid water, water vapor is present in the atmosphere. Bertaux and his colleagues used an infrared detector to estimate the amount of water present around the planet and they discovered a particularly "damp" region just above the equator.
At the same time, the team also looked at the wind speed and discovered that the winds near the damp spot were about 18 percent slower than in surrounding regions. This region seemed way too special.
They looked at how the winds and water might be connected to the high altitude of Aphrodite Terra, and discovered that large waves in the atmosphere crash on the relief like sea waves on a shore, slowing down the high-altitude winds and helping push up the water vapor from the lower atmosphere.
"This certainly challenges our current General Circulation Models," said Håkan Svedhem, ESA Project Scientist for Venus Express, in the statement. "While our models do acknowledge a connection between topography and climate, they don't usually produce persistent weather patterns connected to topographical surface features. This is the first time that this connection has been shown clearly on Venus – it's a major result."