Today, the Central Meteorological Observatory issued an orange warning of blizzard?

This phenomenon should happen in cities.

When it snows, the clouds in the sky are thicker and lower, and the air humidity is higher. The light emitted by street lamps and landscape lamps in cities can be directly scattered or reflected from the ground, which can illuminate the sky. Water vapor in the air refracts and absorbs light. The refraction absorption of red, orange and yellow light with longer wavelength is weak, while the refraction absorption of blue and purple light with shorter wavelength is strong. Blue and purple light in the light are absorbed, while red, orange and yellow light can travel far. At the same time, snowflakes falling in the sky have the same effect. Thus, under the mapping of ground lights, the sky turned orange-red.

This is the same reason that the sun turns red when it rises or is about to set, and it is also because the air humidity is high at this time.