Venus the Planet: A Runaway Greenhouse Effect
1) It cannot rain. There is very little water vapour in Venus' atmosphere and it is not possible for it to form into liquid. Water boils at 100 degrees celsius, so liquid water has not been seen on Venus for a long time. It's even hot enough to melt lead. The atmosphere is acting as a very thick blanket. The energy from the sun goes into the atmosphere, but very little can escape. 
2) Organic life cannot be sustained. Organic life as we know it relies in part on proteins and the chemical reactions needed to produce them. The surface temperature of Venus is sufficient to coagulate (destroy the structure of) virtually all the proteins we and other earthly organisms rely on for normal bodily functions. 3) The clouds trap the sun's heat. This is the most important feature of Venus the planet. The very thick clouds absorb the sun's light and turn it into longer wavelength heat. However, this heat is not easily released as the atmosphere reflects it back down to the surface of the planet instead of allowing it to escape into space. The situation on Venus is called a run-away greenhouse effect. The heating of the atmosphere has reached such a point that it is no longer possible for it to cool; the gases in the atmosphere cannot condense to liquids since it is too hot. That thick atmosphere is a super solar greenhouse that traps more heat, which further reduces the possibility of condensation, and so on. Pictures of the surface sent back by the Magellan probe showed nothing but barren rock. For more details on Venus, this is an excellent site: Details of Venus. |
