# Is a planetary 'temperature inversion' plausible?

It was disputed in the 1940s-50s whether Venus

1. had a hot surface and cool cloud layer or
2. a cool surface and hot cloud layer.

As I recall, both were considered at the limits of plausibility at the time. We know that Venus turned out to be case 1.

But is case 2 still a plausible type of planet, with some other atmospheric conditions?

Bonus: Can you make this inversion such that the surface isn't just cooler than the atmosphere, but cooler than a vacuum world would be?

Edit: Not a complete answer, but I just came across https://en.wikipedia.org/wiki/Anti-greenhouse_effect That said, I already knew that some phenomena (IE, atmospheric particulates) could raise albedo and thus cool the planet. What that page does not explicitly answer is...

A. Can / does a high-albedo atmospheric layer (one that would be noticeable from space as a 'surface', unlike Earth's ozone layer) have a higher temperature than the surface?

B. Is it plausible to have a natural atmosphere where the anti-greenhouse effect dominates over any greenhouse effect that's likely also present? Wiki article says this is not the case for Titan.

Normally the atmosphere is transparent to most of the radiation coming from a star, and thus the only way for the atmosphere to be heated up is by heat exchange with the surface of the planet, absorbing the radiation and re-emitting it at lower frequencies.

This is why the temperature decreases with increasing the height above the sea level on Earth.

If you want to have an higher layer at a higher temperature than the ground you need to have a heat source. Since you cannot rely on stellar radiation, your other option is some exothermic chemical reaction.

For example, again on our planet, $$2 \ O_3 \ \vec \ \ 3 \ O_2$$ releases energy and keep the stratosphere at higher temperature, preventing its mixing with the troposphere.

The stratosphere is stratified in temperature, with warmer layers higher and cooler layers closer to the Earth; this increase of temperature with altitude is a result of the absorption of the Sun's ultraviolet radiation by the ozone layer.

• Not really what I was thinking of. My main interest is whether you can create an anti-greenhouse-effect. – Tristan Klassen Dec 27 '18 at 19:14
• By 'anti-greenhouse', do you mean the opposite of Earth's current greenhouse effect? – kineticcrusher Dec 28 '18 at 16:13
• Look at my original post: "cooler than a vacuum world would be". Basically, an atmosphere that blocks more heat from reaching the surface than it traps. – Tristan Klassen Dec 30 '18 at 20:15