Profile of Venus Help (page 2)

By — McGraw-Hill Professional
Updated on Sep 16, 2011


When astronomers used spectroscopes to analyze the atmosphere of Venus by looking at the light reflected from the planet’s clouds, they knew that the air on that world consists largely of carbon dioxide. This led them to suspect that Venus must be much hotter than Earth because carbon dioxide is well known for its ability to trap heat. It was not until space probes gave the planet close examinations that the truly Hades-like nature of the atmosphere was determined. While the air itself contains mainly carbon dioxide, especially near the surface, the clouds are laden with sulfuric acid.

The clouds that surround Venus are different from those in Earth’s atmosphere in almost every possible way. Much of Earth’s surface is obscured by overcast, but there are always clear spots through which the surface can be seen from space and through which direct sunlight can pass. This is not the case on Venus, at least not at the visible wavelengths. As seen through the most powerful Earth-based telescopes, Venus looks like a cue ball. At ultraviolet wavelengths, details in the clouds can be seen, and from analyzing such views it has been determined that the upper equatorial clouds race around the planet approximately once in every 100 Earth hours.

The clouds on Venus exist in a single layer several kilometers thick and much higher above the surface than any clouds on Earth (except the noctilucent clouds sometimes seen in Earth’s stratosphere). No place on the surface of Venus is ever subjected to direct sunlight. The sky appears angry because of the orange color produced by the sulfur compounds. The winds at the surface of Venus are light, at least in an absolute sense, never moving more than a few meters per second. However, because the air at the surface is thick, a breeze that would be a whisper on our planet carries considerable force on Venus. Perhaps the landscape on Venus is subjected to an ongoing severe thunderstorm with sulfuric acid “rain” that evaporates before it can get down to the surface. Figure 5-3 provides a comparison between Earth’s atmosphere and that of Venus.

Mercury and Venus Twilight Stars Atmosphere

Figure 5-3 A. Earth’s atmosphere.

Mercury and Venus From Earth To Mercury

Figure 5-3 B. The atmosphere of Venus.

Practice problems of this concept can be found at: Mercury and Venus Practice Problems

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