Why is Urumqi foggy in winter?

This has much to do with the formation of fog.

Generally, it is because the cold air near the ground condenses the water vapor in the air and produces fog, so the fog in autumn and winter is relatively large in the morning.

Another important reason for a city like Urumqi is the serious air pollution, so the air you breathe outside feels a little smoky. In winter heating, pollutants such as smoke, dust, suspended solids and automobile exhaust are not easy to diffuse under the conditions of low air pressure and low wind power, and it is easy to form smoke (fog) when combined with water vapor in the lower air, and this smoke (fog) often lasts for a long time.

It is best to wear a mask when going out, which is good for your health and can prevent colds.