On Earth over the course of time, a permanent cloud envelops the planet due to various reasons. However, unlike a nuclear winter or permanent ash cloud situation that completely blots out the sun, this cloud is opaque to a degree. Sometimes there's space/gaps in-between the clouds like a normal day, so sunlight can shine through them and once could see the sun. Other times the cloud is more solid/thick like. Essentially a cloudy or rainy day but with a little more sunlight and brightness than we see normally here on Earth.

At any given point on Earth, there is never a spot that is cloud free or fully exposed to open air.

Would such an opaque cloud coverage cause a nuclear winter/ice age effect where the temperature of the planet drops drastically?

Drastically in this sense means that the temperature falls so much that the effects are catastrophic for the environment. Slightly colder weather wouldn't be considered drastic. One can assume that there are still things like rain and snow fall like normal.


1 Answer 1


In itself, yes. Blotting out the sun produced, famously, the Year Without a Summer, where tropical regions saw snow. And note that this is estimated to have been a drop of, on average, 0.4–0.7 °C (0.7–1 °F).

The question is what is causing it. If the cloud cover, unlike volcanic ash, retains heat more than the current atmosphere does, it might counterbalance the effect.

  • 1
    $\begingroup$ This is one of the reasons why Venus is so incredibly hot. It's atmosphere is opaque, which prevents sunlight from reaching the surface, but it also retains heat very well. $\endgroup$
    – Jafego
    Commented Nov 12, 2022 at 7:35
  • 2
    $\begingroup$ It's hotter than Mercury $\endgroup$
    – Mary
    Commented Nov 12, 2022 at 18:24
  • $\begingroup$ Is there a certain type of element or general type of cloud composition that would lead to just general cold weather but not outright cause a thermal runaway or mass cool down situation? Like a goldilocks zone of sorts. I don't mind that that surface of the planet gets a lot more snow, but life surviving is generally my goal. Thermal or ice age runaway would be problematic for such a setting $\endgroup$
    Commented Nov 13, 2022 at 6:02
  • $\begingroup$ Depends on the specific heat of the substance. You could probably handwoven that part. $\endgroup$
    – Mary
    Commented Nov 13, 2022 at 14:03

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