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Venus, the second planet in our solar system, has a mass MPLANET of 4.87x1024 kg

ID: 3279729 • Letter: V

Question

Venus, the second planet in our solar system, has a mass MPLANET of 4.87x1024 kg and a radius rPLANET of 6,050 km. The Venusian atmosphere is comprised of 96.5% carbon dioxide and 3.5% nitrogen by partial pressure. The pressure and temperature of the atmosphere at the planetary surface is 9.2x106 Pa and 740 deg K. Venus has a tropopause at 65 km, where the temperature is 240 deg K.

(a) What is the density of the atmosphere at the surface of Venus? (b) At what elevation is the atmospheric temperature comparable to Earth’s surface temperature of 287 deg K? What is the Venusian atmospheric pressure at this elevation? Be sure to compute the physical constants for Venus, rather than dialing them up on an electronic device.

Explanation / Answer

A. density of the air at the surface is 67 kg/m3

B. On Venus the average solar flux over the surface is S=2644 W/m2 and the albedo A = 0.8 (sigma = 5.67 X 10 -8 W/m2/K4 for all planets).  

S(1-A) / 4 = sigma TE4
= 220K

The effective radiating temperature of Venus is colder than Earth's because the albedo of Venus is so high