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NomenNescio13 t1_jc2rx4b wrote

Replying to jhairehmyah (#2,220,954)

That was my first thought as well, but I wonder—in the spirit of the question—wouldn't that just be rain?

(This is obviously for OP to answer, the rest of us can only guess as to their meaning.)

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DrSmirnoffe t1_jc2sdyt wrote

Replying to jhairehmyah (#2,220,954)

More intensely at the poles, since the equator's typically too hot for bodies of "methanum" (that's what Atlas Pro coined to refer to liquid methane). In fact, despite Titan being a very cold world, most of the surface isn't cold enough for methane to condense into a liquid state, so the poles are typically where you'll find lakes of methanum.

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Zondartul t1_jc2urj2 wrote

Replying to NomenNescio13 (#2,221,338)

We distinguish rain, snow, slush and hail by the phas-of-matter and composition of the falling "water"... as alternatives to "falling" water, we have fog, dew, jack frost, icycles... different ways for water to arrive on something. We also have different end results: puddle, mud, snow, black ice.

Differentiating precipitation by the chemical that falls is easy (we have water, acid, ash, and fish here on earth) but I find the different physical processes of precipitation also interesting. For example, frozen CO2 (aka dry ice) sublimates into gas, and the opposite process (deposition?) would be interesting to see.

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SmiTe1988 t1_jc2vlt1 wrote

K2-141b

Its surface, ocean and atmosphere are all made up of rocks, which fall like rain and melt into its huge seas. Two thirds of the planet is stuck in perpetual, blazing daylight from the orange dwarf star that K2-141b orbits around.

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aphilsphan t1_jc2znif wrote

Replying to Zondartul (#2,221,449)

CO2 deposition would occur at the Martian poles. The dry ice sublimes when the temperature gets high enough and deposits again when it gets colder. This drives a lot of the changes in atmospheric pressure.

I’d like to see a planet with enough pressure and the right temperature range for CO2 to be a liquid. I’m sure there are ammonia dominated planets.

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sir_jamez t1_jc33tex wrote

Any conditions with extremes and compounds where cells butt against each other and form self-contained weather loops suspended vertically.

E.g. A heavy hot gas layer with a lighter "water" layer above it (or whatever the precipitation medium is); so the precipitation collects, falls, hits the hotter bottom layer, and evaporates up to condense and collect again without ever reaching the surface of the planet. From a surface observer's POV (within or below the hotter gas layer), this would be a continuous rain event that never reaches them and just loops itself in the sky.

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OlympusMons94 t1_jc3jq6v wrote

Replying to aphilsphan (#2,221,645)

CO2 near Venus' surface is a supercritical fluid, which is neither gas nor liquid, but has properties of both. At present, the CO2 is more gas-like, but in the past Venus' surface pressure may have been even higher, possibly enough to support a more liquid-like supercritical CO2 (Bolmatov et al., 2014).

There is also supercritical CO2 within Earth's crust. Supercritical and even actual liquid CO2 are released by hydrothermal vents on the sea floor.

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OlympusMons94 t1_jc3ndu7 wrote

On Earth, volcanic or man-made gases can lead to acid rain, with a bit of strong acids such as sulfuric acid (H2SO4) dissolved in water. On Venus, there is very little water. What little is left has mostly combined with SO3 to form H2SO4. The clouds and rain are made of very concentrated, even anhydrous (no water as a solvent), sulfuric acid. This rain never reaches the surface. Because of the heat, it evaporates before reaching ~30 km altitude. (A phenomenon called virga, which is common with H2O on Earth when the surface air is very dry.)

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puffic t1_jc3tjem wrote

Replying to DrSmirnoffe (#2,221,356)

I don’t think that’s correct as there’s very little difference in surface temperature between the poles and equator on Titan. It probably has more to do with Titan’s long seasons and it’s axial tilt. In any case there are equinoctial storms in Titan’s tropics, but the liquid methane seeps into the dry surface. There is some evidence that it flows back poleward within subsurface aquifers.

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drunkondiscordia t1_jc3udh8 wrote

Iron rain on Wasp-76b

Exoplanet Wasp-76b orbits so close in to its host star, its dayside temperatures exceed 2,400C - hot enough to vaporise metal.

The planet's nightside, on the other hand, is 1,000 degrees cooler, allowing those metals to condense and rain out.

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Realistic-Praline-70 t1_jc42t5l wrote

Precipitation can be almost anything depending on the pressures and climates. It can continually rain stone if there is planet wide long term volcanic activity and like others have stated methane rain happens in our own solar system. Also there are clouds of sulfuric acid on venus

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Washburne221 t1_jc5jr4t wrote

On Io, Jupiter's moon, extreme tidal forces produce intense volcanic activity. But because of its distance from the sun the surface is quite cold (-130 C) and the volcanic gasses released literally freeze out of the atmosphere, producing drifts of sulfur dioxide snow, which can be revaporized by flows of molten sulfur from the volcanoes. So Io has a sulfur cycle.

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zekromNLR t1_jchro7m wrote

Replying to aphilsphan (#2,221,645)

If Venus were cooled to a sufficiently cold temperature (to achieve that, most of the sunlight that hits it would need to be blocked), most of its supercritical CO2 atmosphere would condense out into an ocean of liquid CO2, that would then freeze over into a crust of dry ice hundreds of meters thick.

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