How is the sunset glow formed?

The formation of sunset glow is due to the scattering of light by air. When sunlight enters the atmosphere, it will scatter when it meets atmospheric molecules and particles suspended in the atmosphere. These atmospheric molecules and particles themselves do not emit light, but because they scatter sunlight, each atmospheric molecule forms a scattered light source.

When the sun rises or sets on the horizon, the light reaches the ground obliquely, that is, the angle with the ground is very small. At this time, the sun will reach the ground through the atmosphere thicker than at any time of the day.

At this time, the short-wavelength blue, purple, and even indigo and green light have been scattered very little in the long process of crossing the atmosphere, and the remaining long-wavelength red, yellow, and orange light can "pass through the customs" and enter our eyes. This is the color of summer that we usually see.

Extended data

If there are clouds in the sky at this time, the clouds will be dyed orange, which is a beautiful fiery red cloud.

The closer to the horizon, the thicker the atmosphere through which sunlight passes, the longer the wavelength of light that can "escape" and the redder the glow; On the contrary, the closer to the sky, the bluer the sky becomes.

In addition, the water vapor in the air will also affect the color of rosy clouds. When there are many impurities in the air, such as dust and water vapor, its color is more obvious.

Whether the glow is significant generally reflects whether there is a lot of water vapor in the atmosphere. No matter whether there is bright red rosy clouds before or after sunrise or sunset, it means that the atmosphere contains a lot of water vapor.

The more dust vapor in the atmosphere, the stronger the scattering effect and the redder the smog. The less dust vapor, the closer the haze is to cyan and white.

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