The atmospheres of Mars, Venus and Jupiter.

The general properties of the atmospheres of Mars, Venus and Jupiter are reviewed. The evolutionary processes of planetary atmospheres are outlined as an introduction to a detailed discussion of the structure of the atmospheres of other planets. The most recent observational results indicate that the surface pressure on Mars could be as low as 20 mb, and the amount of CO2 may have a mixing ratio as high as 25% by volume. For Venus, the Mariner II results suggest that the surface temperature may actually be of the order of 600 degrees K. Also there are indications that the surface pressure on Venus could be approximately 100 atm., with the atmosphere mainly composed of N2. In the case of Jupiter, recent theoretical investigations of the atmosphere below the clouds suggest, that there may be regions in the atmosphere of very high density and pressure but at relatively low temperature, creating conditions possibly favorable to the occurrence of complex organic reactions.