🫗 On Venus, the flow from our earthly faucets is reproduced over 6000 km (3728 mi)

On Venus, a huge cloud mass spanning 6000 kilometers (3728 miles) looms over the planet, but its origin remained unknown until today. The key lies in a familiar mechanism: the same one observed when water flows from a faucet into a sink.

This cloud formation was discovered in 2016 by the Akatsuki probe from the Japanese space agency. It sits about 50 kilometers (31 miles) high in Venus's dense atmosphere, stretching along the equator with a remarkably sharp leading edge. Scientists have long sought to understand its impressive size, speed, and that very distinctive shape.


The answer lies in a phenomenon called a hydraulic jump. Just like water flowing from a faucet into a sink: at the impact point, the flow is smooth and fast, then as it spreads, it slows down and suddenly becomes thicker with a sharp edge. On Venus, a similar process occurs with gas. An atmospheric wave of the Kelvin type moves eastward near the equator. As it slows, it triggers a hydraulic jump.

This jump then generates a powerful upward current of sulfuric acid vapor. This vapor rises to 50 kilometers (31 miles) altitude, where it condenses into a thick bank of sulfuric acid clouds. These clouds then form behind the Kelvin wave that marks the leading edge. This is the first time such a phenomenon has been observed on a planet other than Earth.

The Venusian atmosphere is very different from ours. Rich in carbon dioxide, it exerts an overwhelming pressure of 92 bars (about 1334 psi) at the surface. Moreover, it is in superrotation: it circles the planet in four Earth days, while Venus itself takes 243 days to complete one rotation.


This discovery fills a gap in our understanding of Venus's dense atmosphere. Until now, global circulation models ignored this phenomenon. The research team, led by Takeshi Imamura from the University of Tokyo, plans to integrate this hydraulic jump into more comprehensive simulations. This is a challenging task, as even current supercomputers struggle to handle such a volume of data.

The study's results were published on April 24 in the Journal of Geophysical Research — Planets.