Why is the air pressure higher on sunny days than on cloudy days?

Generally, the atmospheric pressure in sunny days is higher than that in cloudy days, and that in winter is higher than that in summer. Atmospheric pressure is related to the density of air, and the density of water vapor is less than that of air. There is more water vapor in the air on cloudy days, and the air pressure becomes lower! It is dry in winter and humid in summer, and there is a lot of water vapor in the air in summer, so the air pressure is low.