Atmosphere of Venus
The atmosphere of Venus is the layer of gases surrounding Venus. It is composed primarily of carbon dioxide and is much denser and hotter than that of Earth. The temperature at the surface is 740 K (467 °C, 872 °F), and the pressure is 93 bar (9.3 MPa), roughly the pressure found underwater on Earth. The Venusian atmosphere supports opaque clouds made of sulfuric acid, making optical Earth-based and orbital observation of the surface impossible. Information about the topography has been obtained exclusively by radar imaging. Aside from carbon dioxide, the other main component is nitrogen. Other chemical compounds are present only in trace amounts.
Pioneer Venus Multiprobe
Below the altitude of 50 km the temperatures measured by the four probes are identical to within a few degrees. They are between 448 °C and 459 °C (838 °F and 858 °F) on the surface. The ground pressure is between 86.2 bar and 94.5 bar. Nephelometers identified three cloud layers with different characteristics. The most remarkable discovery was that the ratio of argon / argon isotopes much higher than in the atmosphere which seems to indicate that the genesis of the Venusian atmosphere is very different from that of Earth. The reconstituted trajectory of atmospheric probes was determined that the wind averaged a speed of 200 m/s in the middle cloud layer at 50 m/s at the base of these clouds and just 1 m/s at the ground. Overall data from airborne sensors confirmed, while specifying the data obtained by the Soviet space probe Venera program that preceded this mission.