Traditional Culture Encyclopedia - Weather forecast - Why is there fog on the bridge and no fog under the bridge?

Why is there fog on the bridge and no fog under the bridge?

Cold air mainly appears in the upper atmosphere. Because cold air mainly appears in the upper atmosphere, it causes heavy fog on the bridge but no fog under the bridge. Fog refers to water vapor condensation composed of small water droplets or ice crystals suspended in the atmosphere close to the earth's surface. It is a common weather phenomenon.