Daily solar tides drive Venus’s super-fast atmospheric winds, study reveals

A new study reveals that the super-fast winds in Venus's atmosphere are primarily driven by a daily tidal cycle powered by heat from the Sun, playing a much larger role than previously thought.

On Venus, wind speeds exceed 100 meters per second (360 km/h), circulating the planet much faster than its rotation—a phenomenon known as "superrotation." In contrast, Earth's atmosphere rotates nearly at the same speed as its surface.

Previous research examined the mechanisms behind this superrotation but did not fully explain it. The recent study by Lai and colleagues shows that atmospheric tides, driven by solar heating and repeating once per Venusian day, contribute far more to the planet's extreme winds than previously estimated.

DAILY HEATING IS KEY

Fast atmospheric rotation is common on rocky planets close to their star with slow rotations. Venus completes a full rotation in 243 Earth days, yet its atmosphere circles the planet in just four Earth days.

To better understand superrotation, researchers analyzed data from ESA's Venus Express and JAXA's Akatsuki satellites collected between 2006 and 2022. They focused on thermal tides caused by sunlight heating the daytime atmosphere. These thermal tides consist of two main components: daily tides (one cycle per Venus day) and semi-daily tides (two cycles per Venus day).

Earlier studies suggested semi-daily tides played the dominant role in superrotation. However, this new study, which included thermal tide analysis in Venus's southern hemisphere, found that daily tides are the key component transferring momentum to the upper cloud layers.

The findings indicate that daily thermal tides are the primary driver maintaining Venus's extreme winds. While researchers note that further study is needed, the discovery sheds light on Venus's meteorological mysteries and may help study atmospheres of other slowly rotating planets.