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Read the following passage.
Why the Sky is Blue
The scattering of sunlight off the molecules in the atmosphere is responsible for the blue appearance of the sky. Usually, we see light in its full visible spectrum, which appears white to the human eye. However, when light rays are broken or refracted by water in the atmosphere, its colors appear separated. This is because each color has its own wavelength.
The reason the sky appears to be blue was first investigated by British physicist Lord Rayleigh. He discovered that sunlight is scattered by water molecules in the air in the same way that white light is scattered by a prism. The visible light spectrum occupies only the portion of the entire electromagnetic radiation field that we can see. The spectrum includes the colors of a rainbow we can sometimes see in the sky. It ranges from red, classified as the longest wavelength, to violet, classified as the shortest. Since this scattering in the sky is more effective at shorter wavelengths where the blue end of the visible spectrum is, the sky appears to be blue. Although all the colors of the visible light spectrum are present in white sunlight, the blue wavelength is most easily detected by the human eye, due to the angle at which we view sunlight.
As we view the sunlight away from the sun, it is scattered through more atmospheric molecules than if we looked more directly toward the sun. This scattering, called Rayleigh scattering, is predominantly in the blue end of the light spectrum. It is because of the shorter wavelength of blue that the light is more effectively scattered. If we look toward the sun, the full spectrum of white light is more dominant; further from the sun, a deeper blue is visible. In other words, the more air molecules light travels through, the more saturation of color we can detect.
scattering – the process by which things are split apart
spectrum – the band of colors present in light
refracted – changed in direction and speed
wavelength – the distance between two peaks of a wave
range – to vary within certain limits
predominantly – mainly; primarily
saturation – the degree of purity of a colorprimarily
Do the following task.
An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
The passage discusses the scientific reasons for the appearance of a blue sky to the human eye.
Answer Choices
Translate all the new words in the text.
Why the Sky is Blue
The scattering of sunlight off the molecules in the atmosphere is responsible for the blue appearance of the sky. Usually, we see light in its full visible spectrum, which appears white to the human eye. However, when light rays are broken or refracted by water in the atmosphere, its colors appear separated. This is because each color has its own wavelength.
The reason the sky appears to be blue was first investigated by British physicist Lord Rayleigh. He discovered that sunlight is scattered by water molecules in the air in the same way that white light is scattered by a prism. The visible light spectrum occupies only the portion of the entire electromagnetic radiation field that we can see. The spectrum includes the colors of a rainbow we can sometimes see in the sky. It ranges from red, classified as the longest wavelength, to violet, classified as the shortest. Since this scattering in the sky is more effective at shorter wavelengths where the blue end of the visible spectrum is, the sky appears to be blue. Although all the colors of the visible light spectrum are present in white sunlight, the blue wavelength is most easily detected by the human eye, due to the angle at which we view sunlight.
As we view the sunlight away from the sun, it is scattered through more atmospheric molecules than if we looked more directly toward the sun. This scattering, called Rayleigh scattering, is predominantly in the blue end of the light spectrum. It is because of the shorter wavelength of blue that the light is more effectively scattered. If we look toward the sun, the full spectrum of white light is more dominant; further from the sun, a deeper blue is visible. In other words, the more air molecules light travels through, the more saturation of color we can detect.
Fill in the diagram and summarize the text using it.
Theory:
Support:
1.
A. 2.
B. 3.
- Theory: Molecules in the atmosphere scatter color in sunlight
- Support A. 2: Rayleigh discovered sunlight is scattered by water molecules in the atmosphere.
- Support B. 3: He found that light scattered is mostly in blue part of spectrum, giving sky blue color.
