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The average surface temperature of Venus is said to be 460 degrees Celsius.

What I'd like to know, is that the temperature of the air in contact with and near the surface, or is that the temperature of the rock surface of Venus? If it is the atmospheric temperature, what is the temperature of the rock surface of Venus?

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    $\begingroup$ We have only temperature measurements made by a lander using a sensor exposed to the venusian atmosphere. No rover measuring a rock surface temperature. $\endgroup$
    – Uwe
    Commented Mar 8, 2020 at 15:29
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    $\begingroup$ VENUS HOT OUTSIDE, COOL INSIDE? By Astrobiology Magazine - Sep 24, 2010 astrobio.net/venus/venus-hot-outside-cool-inside $\endgroup$
    – A. Rumlin
    Commented Mar 8, 2020 at 16:59
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    $\begingroup$ @A.Rumlin This is a fine example of a wrong interpretation. When the interior effectively cools down, that doesn't mean it becomes cooler than the atmosphere ! $\endgroup$
    – Cornelis
    Commented Mar 8, 2020 at 21:37
  • $\begingroup$ It may be useful to study Venus weather. It rotates very slowly and has a CO2 atmosphere, essentially an oven. So unless the oven changes much, the surface temperature of the roast will be similar. (Airflow patterns from pole to equator would be of interest, local weather variation may not be anywhere near earth). $\endgroup$
    – Robert DiGiovanni
    Commented Apr 3, 2021 at 17:52
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    $\begingroup$ The surface of Venus will match the lower atmosphere, exactly. Simply because the atmosphere is so silly dense, it might as well be a liquid. It's like expecting the sea floor to be a different temperature than the seawater that is touching it. $\endgroup$
    – CuteKItty_pleaseStopBArking
    Commented Apr 17, 2021 at 18:59

2 Answers 2

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From the article New: Hot Map of Venus, that I found in this answer:

VIRTIS looked through the thick carbon dioxide curtain surrounding Venus and detected the heat directly emitted by the hot rocks on the ground. The instrument made use of the so-called infrared spectral "windows" present in the Venusian atmosphere. Through these windows thermal radietion at specific wavelengths can leak from the deepest atmospheric layers, pass through the dense cloud curtain, and then escape to space, where it can be detected.

(Emphasis by me)

This can be confirmed by some passages from the article Venus Atmospheric Thermal Structure and Radiative Balance:

At wavelengths of 0.8-2.4 $\mu$m, the H$_2$SO$_4$ clouds are translucent. Aerosols are almost non-absorbing and their scattering properties have little variability with wavelength. The altitude of the origin of the night side emission is wavelength dependent and varies from the very surface at 1$\mu$m to ~35 km at 2.3 $\mu$m.

The lower atmosphere is opaque at infrared wavelengths, with CO$_2$ being the principal source of absorption at wavelengths near 2.0, 2.7, 4.3, 4.8, 5.2, and 15 $\mu$m.

H$_2$O also absorbs in the 2.2-2.5 $\mu$m range. Furthermore, the water vapor detected at this wavelength is from just below the clouds, while H$_2$O absorption at 1-1.2 $\mu$m comes from the atmosphere immediately above the surface.

(Emphases by me)

These passages show, with other absorption wavelengths mentioned in the article, that in the infrared spectrum shown in Fig. 31, the emission at 1 $\mu$m comes from the very surface !

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We don't have proper readings from both, but entropy will tend to level the two out. They aren't always perfectly equal though! The most well known example is that of the seasons on Earth. The peak of summer comes after the solstice because of the ground's absorption of heat. But the relative temperature of the ground and atmosphere is roughly 0.

You may wonder why the ground feels colder to the touch than the atmosphere. That's because the ground conducts heat faster than the air around you. But they are the same temperature.

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    $\begingroup$ Welcome to Space! Your reasoning is sound, but an answer supported by evidence is preferred. (I am not the down-voter, sorry about that.) $\endgroup$
    – DrSheldon
    Commented Apr 2, 2021 at 20:58
  • $\begingroup$ We don't have any measurements of the temperature of the surface of Venus, so reasoning is the best we can do for now. Should I edit the answer to make this more clear? $\endgroup$
    – Wesley Adams
    Commented Apr 2, 2021 at 21:16
  • $\begingroup$ Yes, I would edit the answer to say that they should be the same temperature in theory, rather than claiming they are the same temperature. $\endgroup$
    – DrSheldon
    Commented Apr 2, 2021 at 21:28
  • $\begingroup$ You can also mention that there are at least some measurements of non-zero wind speed near the surface (if there are) and stronger winds going up, so you can suggest that mixing will prevent complete stagnation at the surface and there certainly can be a temperature difference between rock below and atmosphere above the surface. And with a day equal to about 172 Earth days. Venus is complicated and I don't know how that figures in, but must somehow ;-) $\endgroup$
    – uhoh
    Commented Apr 3, 2021 at 9:27

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