Why are the clouds around you red when the sun goes down?

The sun is a mixture of red, orange, yellow, green, cyan, blue and purple. Among these colors of light, red light has the greatest ability to pass through the air layer, followed by orange, yellow and green light, and cyan, blue and purple light are the worst. When there are no clouds in the sky, there are few raindrops hanging in the air; At noon, the air layer is very thin, and almost all the red, orange, yellow and green light in the sunlight pass through, only blue, blue and purple light are blocked, and among these lights, blue light reflects the most, so the whole sky is dyed blue.

When the sun rises in the east in the morning, or when the sun sets in the evening, the sun shines on the ground, and the air layer it passes through is thicker than when the sun is at the top at noon. The yellow, green, cyan, blue and purple rays in the sun are exhausted after walking in the air layer not far away, and cannot pass through the air layer. Only red and orange light can pass through the air layer and dye the sky red.