As the saying goes, "it rains when it is yellow, and it is disgusting when it is yellow." Seek an answer

The sky turns yellow mainly because of the precursor of weather change caused by air pressure, partly because of the refraction of light and partly because of the rise of dust. Therefore, the yellow sky mainly means that the weather is about to change, so farmers often say that it is yellow and rainy.

For people with yellow disease, it refers to unhealthy sallow brown, which makes people look sick. The symptoms and signs of yellowing of skin, mucosa and sclera caused by the increase of serum bilirubin concentration are explained from the medical point of view. From the appearance, the most obvious thing is that the skin is yellow. Of course, if you look closely, you can also see that the patient's sclera is yellow. So it still makes sense.