One of the reasons for the reduced visibility in foggy days is that

One of the reasons for the decrease of visibility in dense fog is that dense fog reflects solar radiation.

According to the data of geography control in senior high school, one of the reasons for the decline of visibility in foggy weather is that dense fog has a reflective effect on solar radiation, so it is necessary to slow down.

In spring and autumn and rainy season, under the influence of high-pressure backflow before the arrival of the front, large-scale and long-lasting dense fog often appears.