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Comparative Analysis of Greenhouse Effects on Venus, Earth, and Mars

Learn about the greenhouse effects and atmospheres of Venus, Earth, and Mars. Discover the impact of greenhouse gases and surface temperatures on these planets. Explore radiation laws and the role of water vapor in creating a greenhouse effect on Earth.

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Comparative Analysis of Greenhouse Effects on Venus, Earth, and Mars

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  1. Venus Earth Mars

  2. The surface temperature of Venus is around 460 C (890 degrees F ), the hottest average temperature in the Solar System. This is due to a runaway Greenhouse Effect. The atmosphere of Venus is composed of : 97% CO2, 2% N2 and less than 1% of O2, H2O and CH4 (methane). Since CO2 is a major greenhouse gas, the radiation from the Sun is trapped in the atmosphere of Venus producing an extremely high surface temperature.

  3. The surface temperature of Earth is around 15 degrees C (60 F). It is kept warm by the greenhouse effect. Water vapor is the most important greenhouse gas on Earth and Carbon dioxide (CO2) is second. Methane (CH4) Nitrous Oxide (N2O) Ozone (O3) and the CFCs are also relevant greenhouse gases. The dry atmosphere of Earth is composed of : 78% Nitrogen N2 21 % Oxygen O2 0.9 % Argon (Ar) Less than 0.1 % are the trace gases including CO2. The amount of water vapor in the atmosphere varies from between 0 and 4 %.

  4. Mars: Mean Surface Temperature =-55 C. Unlike the Earth or Venus, the atmosphere of Mars is very thin, about 1% the mass of Earth's atmosphere. Similar to Venus’ Its composition is 95% CO2, 3% N2, 2% Ar and less than 1% O2. James Lovelock (Gaia) suggested that the low abundance of CO2 in Earth’s Atmosphere and the relatively high abundance of O2 is suggestive of life.

  5. Short wavelengths correspond to high photon energy Hot objects radiate more short wave length photons than cooler objects. UV photons have energies above Visible light IR photon energies are lower than visible light photons

  6. The flux of radiation is also referred to as the radiation intensity. It is the amount of radiant energy passing through a surface area each second per unit area.

  7. The Solar constant is 1365 W/m2 This is the average solar energy that reaches the Earth’s upper Atmosphere if the sun is shining directly on a solar collector. If the collector is tilted a bit then the intensity is weaker since it is spread over a larger area.

  8. Assume So=1000 W/m2 What is S if r=2ro?

  9. Assume So=1000 W/m2 What is S if r=2ro?

  10. Assume So=1000 W/m2 What is S if r=.5ro?

  11. Assume So=1000 W/m2 What is S if r=.5ro?

  12. TK=TC+273 TC=TK-273 DTK=DTC The mean temperature of Earth is 15 C. What is this on the absolute temperature scale? ( Kelvin scale)

  13. Radiation Laws As temperature increases wavelength of maximum radiant intensity, lmax, increases. Wein’s Displacemnet Law. Sun Earth

  14. Twice the temperature half the wavelength

  15. Black Body e=1.0

  16. Stefan_Boltzman Radiation Law. As temperature increases total radiation output increases. Brightness = Intensity Energy leaving an object each sec per square meter As T double Brightness increases by ___??____ As T triples Brightness increases by _______

  17. Radiation Laws As temperature increases total radiation output increases. Stefan_Boltzman Radiation Law. Brightness = Intensity Energy leaving an object each sec per square meter As T double Brightness increases by 16 As T triples Brightness increases by _81 times = 3x3x3x3__

  18. Venus T=(2633*(1-.8)/4/5.67e-8)^0.25 = 219 K Mars T=(591*(1-0.22)/4/0.0000000567)^0.25= 212 K Earth T=(1365*(1-0.3)/4/0.0000000567)^0.25= 255K

  19. Magnitude of the greenhouse effect MGE=Tsurface-Teffective radiating temperature Earth MGE=288 K-255K=33K Mars MGE =218K – 212K= 6K Venus MGE= 730K-218K= 512K

  20. Water vapor is the most abundant greenhouse gas and contributes most to the total greenhouse effect of Earth. (about 75% of the greenhouse warming is from water vapor)

  21. Air pressure Air pressure drops by half for each 5.5 km altitude gain

  22. The lapse rate is the temperature drop per altitude change. A lapse rate of 6 oC/km means that the temperature drops by 6 oC for each km increase in altitude. A temperature inversion (increase in temperature with height) would have a negative lapse rate. Air temperature drops with increasing height in the troposphere and increases in the stratosphere. The tropopause (near 12 km) is the transition between the troposphere and stratosphere.

  23. http://www.atmosedu.com/meteor/Animations/42_Selective_Absorption/42.htmlhttp://www.atmosedu.com/meteor/Animations/42_Selective_Absorption/42.html

  24. Low stratus clouds tend to cool Earth’s surface over the course of a 24 hr period because the sunlight reflected by them is more important than the amount of longwave radiation trapped near the surface. The opposite is true for high thin clouds.

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