Simulations of Greenhouse Effect (10 points) Find a computer and start the green
ID: 3751296 • Letter: S
Question
Simulations of Greenhouse Effect (10 points) Find a computer and start the greenhouse effect simulator demonstrated in class: https://phet. colorado.edu/en/simulation/greenhouse. First select the “Photon Absorption” tab. (a) Select infrared photons. Which of the 5 gases do not seem to absorb infrared light? Which of the 5 gases do absorb and re-emit infrared light? (b) Select photons of visible light. Which of the 5 gases do not absorb visible light? Which of the 5 gases do absorb and re-emit visible light? Now switch to the “Greenhouse Effect” tab. (c) Introduce a few clouds. What do clouds do to some of the visible light photons from the sun? What do clouds do to the infrared photons emitted by the earth? Does the surface temperature change significantly when there are many clouds? (d) True or False: Increasing the concentration of greenhouse gases increases the amount of energy radiated by Earth into space. (e) True or False: Cloud reflect about 10% of the sunlight incident upon them back into space. How did you arrive at your answer? (f) True of False: At higher surface temperatures, the Earth’s surface emits more infrared (IR) radiation. Why? (g) Explain briefly in your own words why the average surface temperature of the Earth goes up in the presence of greenhouse gases, even though the incident power from the Sun doesn’t change. (h) Why are there more IR photons emitted by Earth than visible photons incident from the Sun? (i) Using the expressions derived in class, if the fraction f of IR emitted by the Earth that makes it into space decreases from 60% to 50%, what Earth surface temperature do we expect?
Explanation / Answer
a.
The gas N2 and O2 do not seem to absorb and re-emit infrared light.
The gases CH4 , CO2 , H2O seem to absorb and re-emit infrared light.
b. All the 5 gases (CH4 , CO2 , H2O , N2, and O2 ) do not seem to absorb and re-emit visible light.
None of them seem to absorb and re-emit visible light.
c. The clouds don't allow the visible light to reach the earth surface by bouncing it back to space
It doesn't allow the infrared light to leave the earth surface by bouncing it back to the earth surface.
Since there are only 3 clouds and the temperature drops, I assume that the same will happen when there are many clouds, Thus it affects the temperature significantly.
d.True. There are many molecules leaving the earth atmosphere.
e. True, the clouds reflect back the sunlight back into space because as seen in the stimulation some of the light photons are reflected back into space by the clouds.
f. True. because of the increase in the concentration of the greenhouse gas in the atmosphere, there is a rise in the surface temperature thus increase in greenhouse concentration leads to earth surface emitting more IR radiation.
g. The greenhouse gases such as CH4 , CO2 , H2O has the ability to absorb and re-emit the infrared light that is passing through it. Thus even when the Sun incident power doesn't change the power is retained by the greenhouse gases by the greenhouse effect which releases it at night which return increases the surface temperature.
h. This is also due to the greenhouse gases as the absorb the infrared photons and release it the amount of IR released by the earth is more than the amount of IR received by the sun.
i. You didn't attach the formula with this. Hope you get it right.
Clue: Since the amount of IR making into space reduces the surface temperature will increase.