Why is air pressure affected by weather and season?

The air pressure in winter is higher than that in summer, because the thermal expansion air mass rises in summer, which leads to the decrease of ground air pressure.

When the air pressure in sunny days is greater than that in rainy days, it is cold front weather: when the cold air mass crosses the border, it rains and blows, and the temperature drops.

After the cold air mass crosses the border, the area will be controlled by the cold air mass, so the weather will clear up and the air pressure will rise.

Hehe o(∩_∩)o ...

That's all. My ability is limited.