Venus: Atmosphere and Magnetosphere

Atmosphere

Missions to Venus have resulted in extensive information on the planet's atmosphere. The day-side upper atmosphere and ionosphere temperature is approximately 40 degrees Celsius, while the night-side temperatures drop to a chilling -170 degrees Celsius. (Please note that these atmospheric temperatures are different from the planet's surface temperature.) The extreme differences in the day-side and night-side temperatures cause a movement of air from the high to the low temperature. This wind also carries light gases with it, concentrating in a bulge on the planet. The gusty upper-level winds are 360 km/hour and cover the entire planet. Although the upper atmosphere can be measured with relative ease, thick clouds prevent outside observers from ascertaining the winds speeds closer to the surface. Fortunately, researchers can still determine the wind speeds indirectly by considering the movements of probes entering the planet's dense clouds. From the surface to 10 km, wind speeds range between 3 and 18 km/hour.
The surface pressure on Venus is 96 bars as compared with Earth's 1 bar. Carbon dioxide dominates the planet's atmosphere at 96 percent. Nitrogen accounts for more than 3 percent. The remaining fraction of a percent includes sulfur dioxide, hydrogen fluoride, water vapor, carbon monoxide, neon, argon, helium, chloride, and hydrogen. The cloud base at approximately 50 km is mostly sulfuric acid.