Why is the sky blue?

The reason why the sky is blue is as follows:

1, and the high-altitude scattered light is mainly purple, blue and cyan light. For molecular scattering in the lower air, blue light is mainly scattered. Therefore, the sky we see is blue. The brighter the weather, the bluer the sky.

2. When the weather is clear, there will be many tiny dust, water droplets, ice crystals and other substances in the air. When sunlight passes through the air, long-wavelength red light, orange light and yellow light can penetrate the atmosphere and directly illuminate the ground, while short-wavelength blue light, purple light and indigo light are easily blocked by particles suspended in the air, making the sky appear blue.

The clear sky is blue, not because the atmosphere itself is blue, nor because it contains blue substances, but because atmospheric molecules and tiny particles suspended in the atmosphere scatter sunlight. Due to the inhomogeneity of the medium. The phenomenon that light deviates from the original propagation direction and scatters sideways is called the scattering of light by medium.

The clearer the weather, the bluer the sky will be. This is because there will be a lot of dust particles, water droplets and ice crystals in the air at this time, and there will be a lot of scattered blue light.

Sometimes the sky looks white, because when the clouds are thick, they will reflect sunlight. At this time, there are many dust particles, water droplets and ice crystals in the air. After sunlight is reflected, the sky will show the colors of dust particles, water droplets and ice crystals, which means that the sky looks white on rainy days.