Why the Sky Is Blue
Written by Studio AM.
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Sunlight looks white, but it is really a blend of many colors mixed together. When that light passes through the air, it does not travel untouched. Light interacts with gas molecules and is redirected in many directions, a process called scattering.
Not every color scatters the same amount. The blue and violet parts of sunlight have shorter wavelengths, which scatter more strongly than the longer wavelengths of red and orange. So as sunlight crosses the sky, blue light is thrown in every direction, filling the whole dome above you. When you look up, that scattered blue is the light reaching your eyes, and the sky appears blue.
The same rule explains the red of a sunset. Near the horizon, light must pass through much more air before it reaches you. Along that longer path, most of the blue has already been scattered away, leaving mainly the reds and oranges to come through. One simple fact about wavelength, then, paints both the blue of noon and the red of evening.
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Question 1 of 4
The passage mainly explains
The answer is D: why the sky looks blue and sunsets look red
The whole passage uses scattering to explain both the blue sky and the red sunset.
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Question 2 of 4
According to the passage, which colors scatter most strongly?
The answer is B: Blue and violet
The text says the short waves of blue and violet 'scatter far more strongly' than red and orange.
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Question 3 of 4
Based on the passage, if the air held no gas molecules, the daytime sky would most likely
The answer is A: look dark without molecules to scatter sunlight
The blue comes from molecules scattering light; with no scatterer, no blue would fill the sky, leaving it dark.
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Question 4 of 4
In this passage, 'scattering' most nearly means
The answer is A: light being redirected in different directions
The first paragraph defines scattering as light being redirected through interactions with gas molecules.
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