Why is the sky blue? Why aren't city skies blue?

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• Why is the sky blue? Why aren't city skies blue?

  The blue appearance of the sky is due to the effect of atmospheric scattering. The following is a brief explanation of this phenomenon: The white light in sunlight is made up of a variety of different wavelengths, including red, orange, yellow, green, blue and purple. When this light enters the Earth's atmosphere, it interacts with gas molecules and suspended particles. When sunlight hits Earth's atmosphere, blue light has shorter wavelengths than other colors and is therefore more likely to collide with atmospheric gas molecules, mainly nitrogen and oxygen. These collisions cause blue light to scatter, scattering blue light in all directions to the observer's eye. In contrast, other colors of light have longer wavelengths, so they scatter relatively little in the atmosphere. This explains why we see a blue sky during the day, because blue light scatters the most and dominates the sky. However, when the sun is at sunset or sunrise, the sunlight has to take a longer path through the atmosphere, and more scattering occurs, leaving more blue light scattered and less red and orange light scattered. This is why the sky appears orange or red at sunrise and sunset. In general, the sky appears blue because the blue light of sunlight scatters through the atmosphere and is eventually perceived by observers. Why aren't city skies blue? A city sky may not look as bright blue as a country or field, but take on a darker or grayer hue. This is due to the following main reasons: 1. Air pollution: particulates and gases released by industrial emissions, vehicle exhaust and other pollution sources in cities will increase atmospheric scattering. These particles and gases scatter light, causing the sky to take on a cloudy or grayish appearance, rather than a bright blue. 2. Light pollution: Artificial lighting and advertising lights in cities can produce strong curtains of light, resulting in excessively bright night skies in cities. This interferes with normal sky viewing and stargazing, making the sky appear darker or grayer. 3. Buildings and man-made structures: Tall buildings and other structures can occupy part of the sky view in the city, blocking part of the sky visibility. This makes the sky look more confined and limited, giving a different feel than the open country or wilderness. Although city skies may not be as clear and bright as those in the countryside, the color and appearance of city skies are still influenced by atmospheric scattering. The scattering of light by particles and gases in the atmosphere affects the color of the sky, giving it the unique character of a city.

  The blue skyWhy the sky is blueLight waveLight pollutionatmospheric scattering

  2023-05-29 13:12:50

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