Venus is considered to be the living proof of Carbon dioxide greenhouse gas global warming. That term was used up to about 2000 but revised to "Climate Change", which means whatever you want it to mean. Anyway, the atmospheric composition is indeed mostly carbon dioxide:
Carbon dioxide 96.5 %
Nitrogen 3.5%
Sulfur dioxide 150 ppm
Water vapor 20 ppm
Since Venus has an atmosphere four times heavier than ours, there is actually about four times more Nitrogen on Venus than Earth. Earth has an average of 0.4% water vapor in the air so those trace amounts of vapor/liquid phase should not be considered irrelevant.
Venus rotates quite slowly, so that one solar day lasts more than 100 Earth days. It turns out that the upper atmosphere facing away from the Sun has a frigid temperature of -170 degrees Celsius that is lower than the freezing point of carbon dioxide (-78 degrees at STP). There is known to be a mist here and there may be other condensed volatile compounds as well. A cubic meter of condensed carbon dioxide should radiate about the same energy as we get from the sun, here on Earth. In other words, if the Sun was removed, it would take a few days for Venus to cool off.
As this cold air falls toward the surface, it heats up according to adiabatic lapse rate. The temperature at 50 km. (31.1 miles) is 75 degrees Celsius. If the adiabatic lapse rate is 8 degrees per kilometer the temperature at the surface is 400 + 75 = 475, exactly as measured.
Since convection is in meters per second and radiation is at the speed of light, this heat should radiate away as fast as it comes in. The boiling point of sulfur is 445 degrees at STP; there is a haze at the surface and right away, there is something here to sort out. A myriad of vaporous and misty things are in the air which condense at about 30 kilometers above the surface, or what is referred to as the "cloud deck". For example, the latent heat of condensation is 2.2 million joules per liter of water. This cloud cover of acid and azeotropes is going to send back considerable heat (at near light speed).
Carbon dioxide is a non-polar molecule, meaning that is "microwave safe". This is definitely not true of sulfuric acid vapor. 40 kilometers of this material is not transparent to heat radiation.
Less than half the sun's radiation gets through the cloud layer, but according to the carbon obsession, some infrared light gets in; but it doesn't get out.
Heat is transferred in many, generally complicated, ways. The greenhouse gas model has no theory and no experimental verification.