Venus's supersonic winds create gusty planet

Scientists think they may have solved one of the great mysteries of the solar system: why the winds on Venus blow faster than the planet's rotation.

Venus rotates once every 243 Earth days, but it takes just four Earth days for clouds in the Venusian atmosphere to go all the way round the planet at speeds of 200 metres per second.

This phenomenon, known as superrotation, is only known to commonly occur on Venus and the Saturnian moon Titan.

Astrophysicists have long speculated that temperature differences between the day and night sides of Venus are what drive these winds.

Now a team of scientists led by Hector Javier Durand-Manterola from the Universidad Nacional Autonoma de Mexico says the winds are being driven by another much faster wind flow, higher above the planet.

Reporting in the physics blog ArXiv.org, Durand-Manterola says winds in the ionosphere between 150 and 800 kilometres above the surface play an important role in superrotation.

These ionic winds were discovered by the American Pioneer Venus Orbiter in the early 1980s.

Supersonic winds

Known as the transterminator flow, the winds travel at supersonic speeds of several kilometres per second, and are thought to be driven by the planet's interaction with solar winds from the sun.

Durand-Manterola says the supersonic winds in the ionosphere generate sound waves through turbulence, which inject additional energy into the atmosphere.

The researchers say their calculations indicate the process puts in more than enough energy to account for the amount lost due to atmospheric viscosity.

They predict the sound waves created by the energy injection have an intensity of 84 decibels.