Suppose the Suns surface temperature suddenly cools to 2000oC. ...

[daltonest1984]

Suppose the Suns surface temperature suddenly cools to 2000oC. Why would the sky appear more red than blue?
  What will be an ideal response?

Question 2

What would have the greatest impact on Earths greenhouse effect: removing all of the CO2 from the atmosphere or removing all of the water vapor? Explain your reasoning.

[CourtneyCNorton]

Answer to Question 1

ANSWER: Based on Wien's Law, if the Sun were to cool to a lower temperature, the Sun would emit a peak in radiation at longer wavelengths. The longer wavelengths would be shifted toward the lower energy red portion of the visible spectrum. At present, the top of Earth's atmosphere reflects shorter blue wavelengths of light. If the Sun's energy spectrum were to be shifted, the Earth's atmosphere would be impacted by longer wavelengths of light and create a redder atmosphere.

Answer to Question 2

ANSWER: Students should describe that removing water vapor would have the greatest impact because water vapor is a strong absorber of infrared radiation and because atmospheric concentrations of H2O are much higher than concentrations of CO2