If the flue gas and the ambient temperature are the same, is it sunny or rainy? Why?

Other conditions being the same, the smoke exhaust capacity of the chimney is greater in sunny days than in rainy days, because the air density in sunny days is relatively small, so the exhaust gas in the chimney is faster.

The higher the ground, the smaller the atmospheric pressure. The higher the chimney, the smaller the air pressure at its outlet, the greater the air pressure difference with the ground, and the easier it is for the smoke to rise, that is, the greater the pumping force.

Because of the pressure difference, first of all because of the height. Secondly, because the gas velocity is high and the air pressure at high places is low, the gas in the chimney will move upward under the action of atmospheric pressure.

The change of atmospheric pressure is related to the weather. At different times, the atmospheric pressure in the same place is not exactly the same. We know that the density of water vapor is less than that of air. When there is more water vapor in the air, the air density will become smaller and the atmospheric pressure will also decrease.

Generally speaking, the air pressure in rainy days is smaller than that in sunny days, and it is found that the sudden drop of air pressure in sunny days is a precursor to rain; However, after several days of continuous rain, it is found that the air pressure has become larger, and it can be expected that it will clear up soon. In addition, the change of atmospheric pressure is also related to temperature. Because the air density decreases when the temperature increases, the atmospheric pressure is smaller when the temperature is high than when the temperature is low.