The
greenhouse effect of Venus
From geometry, we can
calculate the average solar flux over the
surface of Venus. It is
approximately 661 W/m2.
Venus is very reflective of
sunshine. In fact, it has a reflectivity (or albedo) of 0.8, so the planet
absorbs approximately 661 X 0.2 = 132 W/m2.
By assuming that the incoming
radiation equals the outgoing radiation (energy balance), we can convert this into an effective radiating temperature by
invoking the Stefan-Boltzmann law
(total energy = sT4). We find that T=220K.
But
VenusŐ surface has a temperature of 730K!!!
The explanation for this huge
discrepancy is the planetŐs greenhouse
effect.