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Given a rotation rate comparable to Venus & axial tilt like Uranus (about 90deg), what should I expect for atmospheric winds? I anticipate a stratospheric wind only, dropping to the surface at or near the terminator (only), but not much in the way of storms, due to low Coriolis effects. Am I wrong?

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Super-rotation

As I wrote in an answer to another question about winds, studies of slow-rotating planets like Venus have yielded information about what we should expect for planets like this in general:

  • The troposphere may exhibit something called super-rotation, meaning the atmosphere rotates faster than the planet. This will cause fairly strong latitudinal winds at about 100 km up; for Venus, these winds may be a couple hundred miles per hour.
  • The Coriolis force is so low because of the planet's slow rotation speed, so instead the centrifugal force is the main influencer of the pressure gradient in the atmosphere; this contributes to wind direction differently than on a fast rotator like Earth.

I should note that super-rotation is a highly complex phenomenon that is influenced by a number of factors, among them Venus' high temperatures and thus extensive Hadley cells. However, the phenomena which I've described should be applicable to any slow rotator, to various degrees. They may be weaker on planets with lower surface temperatures, but

Storms

Your argument about large-scale cyclonic activity being absent because of the low Coriolis force is correct. Hurricane-like storms require the Coriolis force to form, and as Venus' angular velocity is about 0.4% of Earth's, the Coriolis force should be over two orders of magnitude weaker. We can assume that they effectively do not exist.

Now, non-hurricane-like storms should still exist on Venus. Lightning may have been observed on a number of occasions, but there is not yet firm proof of it. The nature of the storms on your planet will depend on the composition of the atmosphere and thus the composition of the clouds. Thunderstorms are likely to exist nonetheless.

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