Weather signs in Yang Sha.

The three horizontal bar hooks are signs of blowing sand, as shown in the following figure:

Sand blowing refers to the weather phenomenon caused by local or nearby dust being blown by the wind. Visibility is obviously reduced during sand blowing, and the sky is cloudy and yellow when it appears. The north is easy to appear in spring. The wind is strong in sand-blowing weather, which affects the visibility between 1 km and1km.

In order to make it easy for the public to understand and identify, a set of graphic images representing weather phenomena has been formulated for TV or other public media.

The three horizontal lines represent the "fog" that often brings disasters to aviation, navigation and road transportation. Refers to a large number of water droplets or ice crystal particles suspended in the air near the ground. When this aggregate reduces the horizontal visual distance below 1000 meters, it is called fog; When the visible distance drops to 1000 ~ 10000 meters, it is called light fog.

Brief introduction of aeolian meteorology

Sand blowing is caused by local or nearby dust blown by the wind, and the dust concentration in different directions is inconsistent; Most of the floating dust comes from distant dust spread by high-altitude airflow (non-local dust is blown by the wind), or from fine particles floating in the air after dust storms and sand blowing, and the dust content in all directions is relatively uniform.

The appearance of floating dust always lags behind sand blowing, that is, when floating dust appears, it must be sand blowing or sandstorm in remote or local areas. If it is local sand blowing, then the sand blowing phenomenon must have ended when floating dust is recorded.

When there is a sandstorm, the air will be quite turbid. When the vertical visibility is greatly affected, the sun appears khaki, and when the vertical visibility is slightly affected, the color of the sun changes little. The distant prospect is covered with khaki.