What does the eight-character dust that covers the sun mean?

Eight-shaped dusty sky means that when there is a strong cyclone or strong cold air in the north that brings a windy weather system and passes through the sand source, the dust is very heavy, which will make the sky full of dusty weather under the action of strong wind. The word means to keep people away from windy weather by blocking the sky and sunshine, rather than being directly affected by strong winds.