The weather phenomenon caused by heating in northern cities is

The weather phenomenon caused by the supply of northern cities is smog. Because the winter in northern cities is colder than that in the south, the temperature is below minus 10 degrees, and the temperature in the farther north can reach around minus 20 or 30 degrees, or even lower. Every household needs to raise the indoor temperature, so there is central heating. The principle of heating is to boil water with a boiler, turn the water into steam, and then transfer the heat of steam to every household through the heating pipe. In the northern cities of China, coal-fired boilers are mainly used for heating. There are many heating companies in every city, and there are countless large and small coal-fired boilers. After burning coal, smoke and dust are discharged into the air, which pollutes the air. Because northern cities are big coal users in winter, coal-fired boilers of all sizes discharge untreated smoke into the sky every day, causing the emission of PM2.5 in the sky to exceed the standard. The air is gray all day, forming harmful haze weather.