What does the weather forecast mean by "S"?

S is floating dust, which is formed by floating in the air after sandstorm or sand blowing in the distance or locally.

Add a ↑ to S to mean blowing sand (to mean rising from the ground).

Add a → to S to indicate sandstorm (meaning to go with the wind).

In the weather with floating dust, the distant scenery is mostly yellow, and the sun is pale or pale yellow.