User talk:Douglas Cotton

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It cannot be substantiated with standard physics that the surface of Venus is kept hot by radiation from the colder carbon dioxide atmosphere. The small solid core of Uranus (55% the mass of Earth) has a surface temperature several times that of the Venus surface, and yet only about as much methane as Earth has water vapor. Uranus is nearly 30 times further from the Sun than Earth is, and thus receives little more than 0.1% of incident solar radiation.

In fact the Venus surface temperature rises by about 5 degrees (from 732K to 737K) during the four-month-long day and so this requires an input of thermal energy, which cannot be coming from the colder atmosphere because, if it were, entropy would be decreasing.

Venus cools by 5 degrees at night, and so it could easily have cooled right down over the life of the planet if the Sun provided no insolation. So we can deduce that it is energy from the Sun which is gradually raising the temperature of the Venus surface during those four months of Earth time. But less than 20 watts per square meter of solar radiation gets through to the surface because carbon dioxide actually absorbs incident solar radiation.

If one tries to explain the 5 degree difference with Stefan-Boltzmann calculations for radiation, there is a difference of about 450 watts per square meter just between the two temperatures 732K and 737K, and so this is not supplied from the direct solar radiation which is only about one tenth of that which reaches Earth's surface.

Hence there is no scientific basis for assuming that direct radiation to the surface is the cause of the high surface temperatures on Venus.

Douglas Cotton (talk) 10:02, 31 March 2014 (UTC)