Summary

The atmosphere of Venus is quite different from that of Earth: it is much hotter and denser. The temperature and pressure at the surface are 740 K and 92 atmospheres respectively. Its atmosphere is primarily composed of carbon dioxide (96.5%) and nitrogen (3.5%), the rest being trace gases such as carbon monoxide (CO), water vapor (H₂O), halides (HF, HCl), sulfur-bearing species (SO₂, SO, OCS, H₂S), and noble gases. Sulfur compounds are extremely important in understanding the formation of the Venusian clouds which are believed to be composed of sulfuric acid (H₂SO₄) droplets. These clouds completely enshroud the planet in a series of layers, extending from 50 to 70 km altitude, and are composed of particles of different sizes and different H₂SO₄/H₂O compositions. These act as a very effective separator between the atmospheres below and above the clouds, which show very distinctive characteristics.