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I was surprised to learn recently that Neptune has winds of 1500 miles an hour.
My question is whether life could ever evolve on such a Planet that has such powerful winds? Not necessarily on Neptune of course but on another exoplanet in another Solar System.
We know that life can start and evolve quite well on a planet with 250 mph winds: You're living on one. The jet stream can reach this speed in the Earth's atmosphere.
Beyond that it is speculation. While not much is going to survive on the surface if there are surface winds of 1500mph at a static pressure of anything like 1atm, I can see no problem of life developing in the depth of the ocean no matter what the wind speed is.
However I futher suggest that 1500mph winds cannot happen at the surface of a terrestrial planet that is anything like the Earth. The extreme conditions needed to create a surface wind of 1500mph on a daily basis may prevent any kind of life as we know it. But then the winds are not the acutal problem but the conditions needed to produce them.
From memory, there was a question asked whether life would be possible on Neptune (which isn't your question but I mention it here anyway) and the answer was that it was probably improbable, because by the time you get deep enough inside Neptune to find liquid water, the pressure and temperature are too high to be good for life to form, even as extremophiles. People will sometimes respond to that by saying "life as scientists know it", so, sure, many things are possible, but the chemistry of life is sufficiently difficult that I believe "basically no chance" is a more likely outcome than "maybe life that we haven't considered exists out there" . . . but I'm getting sidetracked.
Life, we think, evolved in the oceans, so high wind speed wouldn't affect the emergence and growth of life on an Earth-like planet. It only begins to be a factor when life tries to move onto land and even then, I think, under the right conditions for life to evolve, bacteria or mosses could adapt to high wind speed. Smaller life forms could evolve with hooks of some kind to keep from being blown away. Wind speed that high could be a deterrent, but not necessarily enough to stop all life on land.
Extreme wind speed is driven a few ways, as I understand it. One would be rapid rotation, in the case of gas giants, Jupiter and Saturn, generating a strong Coriolis effect and multiple Hadley cells. Earth has 3 Hadley cells per hemisphere, Venus, with essentially no Coriolis effect to speak of, has one per hemisphere and Jupiter has, I think, 11 her hemisphere. Though we don't know what caused Jupiter's great red spot, it's Hadley cells help maintain it.
In case case of Neptune and Uranus, smaller Coriolis effect than Jupiter and Saturn but similar and even higher wind speed, the primary driver seems to be a narrow band of evaporation and condensation, where the high wind happens over just the top 2% of the planet.
The scientists discovered the winds blow in relatively thin weather layers no more than 600 miles (1,000 kilometers) deep on both planets. For comparison, Neptune is about 30,600 miles (49,250 km) in diameter, while Uranus is approximately 31,500 miles (50,700 km) wide.
These findings help reveal how these winds originate, researchers said.
Past studies have suggested the winds on Uranus and Neptune might arise one of two ways — either shallow processes in their outer atmospheres, or deeper atmospheric mechanisms extending into their interiors. The researchers found the windy layers of Uranus and Neptune occupy the outermost 0.15 and 0.2 percent of their masses, respectively, suggesting that shallow processes drive those winds, such as swirling caused by moisture condensing and evaporating in the atmosphere.
On Venus, for example, very high wind speeds are generated in it's jet stream high above the planet, but the engine for those wind is likely the sun and slow rotation of the planet, so you get heated atmosphere on the Sun side of the planet a rapidly cooling atmosphere on the night side, creating an engine for high wind speed but this effect doesn't reach the surface. It's an upper atmosphere effect only. Venus has consistent low wind speed at its surface, suggesting again that evaporation plays a key role in wind speed. Venus has almost nothing to evaporate at its surface.
Mars has higher wind speed than Earth, but a very thin atmosphere. A 100 or 120 kph wind on Earth would have a pretty good chance of pushing a person off their feet. A wind speed 3 times that fast on Mars wouldn't feel like much because the atmospheric pressure is so low so high wind speed but very low atmospheric pressure, I suspect the atmospheric pressure would be a bigger deterent to life than the wind speed - but again, that's just speculation.
I don't want to say it's impossible for a terrestrial planet to have super-wind speed on it's surface. A water world, perhaps might sustain regular hurricane force winds and long lasting storms, but whether a water world qualifies as an Earth-like planet might be debatable. As James_K says, It's unclear to me if an Earth-like planet, with both land masses and a sufficient blanket of atmosphere could generate super-high wind speeds. Maybe, if the conditions are just right, but probably not 1,500 mph. That seems unlikely. I think it's good to keep an open mind about what's still basically unknowns like peak theoretical wind speed on Earthlike planets or how life might adapt if there's life on such planets, but I agree with James K. Winds that high on an Earth-like planet are unlikely.
