When the fog appeared, it was cold and humid, right?

When the relative humidity reaches 100%, the water vapor in the air will condense into fine water droplets suspended in the air, which will reduce the visibility of the ground, so it is called fog. Therefore, fog appears under the condition of sufficient moisture in the air and low temperature.

In autumn and winter, due to the long nights, Feng Yun appears frequently, and the ground heat dissipation is faster than that in summer, which leads to a sharp drop in the ground temperature, so that the water vapor in the air near the ground can easily reach saturation in the middle of the night, condense into small water droplets and form fog. The morning temperature in autumn and winter is the lowest and the fog is the thickest.