In the early morning, when the sun is just coming out, or in the evening when the sun is about to set, the clouds in the sky are often reddish, like fire. People call this reddish cloud, the burning cloud, also called the morning and evening sun. Sometimes, when there are no clouds, the sky is also a fiery red color, which is called a fiery sky.

Fiery clouds are reddish-colored clouds that appear at sunrise or sunset. Fiery clouds belong to the category of low clouds and are one of the phenomena of atmospheric changes. It often appears in the western part of the sky in summer, especially around sunset after a thunderstorm. Due to the strong evaporation from the ground and the large role of updrafts in the atmosphere, the shape of the pyroclastic clouds varies greatly. The color of the pyroclastic clouds is usually reddish. The appearance of fiery clouds signals the approach of a period of warm weather, abundant rainfall and luxuriant biological growth.

Causes in Brief

We already know that sunlight is a mixture of seven colors of light: red, orange, yellow, green, cyan, blue, and violet. These colors of light have different wavelengths, with red light waves being the longest, orange light waves being the next longest, and violet light waves being the shortest. The molecules of the air and the air floating countless tiny dust and water droplets, they are able to the sun's various colors of light dispersed, which is called the scattering effect. The shorter the wavelengths of light waves in sunlight, like violet and blue light, are easily scattered; the longer the wavelengths, like red and orange light, are not easily scattered. In the morning or evening, the sunlight is oblique, it passes through the air layer of the longer distance, by the scattering will be weakened very much. The most attenuated light is violet light, and the least attenuated is red or orange light. These weakened colored sunlight, shining in the sky and on the clouds, will form a bright and colorful haze. When there are no clouds in the sky, there are fewer raindrops hanging in the air; the air layer is thinner at noon, and almost all of the red, orange, yellow, and green colors in the sunlight pass through, stopping only the green, blue, and purple colors, and of these, the blue light reflects the most, so the whole sky is dyed blue.

When the sun rises in the east in the early morning or sets in the evening, the sunlight reaches the ground and passes through a thicker layer of air than when the sun is overhead at noon. Sunlight in the yellow, green, green, blue, purple light, in the air layer in the walk not much far has been exhausted, can not pass through the air layer. Only red and orange light could poke its head through the air layer, coloring the sky red.

Fire clouds can predict the weather, folklore has a proverb "early burn do not go out, evening burn travel thousands of miles", that is, fire clouds or fire sky if the morning, the weather may be bad; appeared in the evening, the next day will be a good day.