Why is cloudy weather depressing?

Atmospheric pressure usually has two meanings: one refers to atmospheric pressure, which is also the most general statement; The second refers to the oxygen concentration, which is a common saying.

The landlord mentioned that "cloudy days are depressing; "Summer low pressure" usually refers to the level of oxygen concentration. Winter is dry and cold, the air density is higher than that in summer, and the water vapor content is lower than that in summer, thus making the oxygen concentration higher than that in summer. The water vapor content in the air on sunny days is much lower than that on cloudy days, so the relative oxygen concentration is higher.

It should be mentioned that the statement of atmospheric pressure here is reasonable. It is cold in winter, with small molecular spacing and high density. When there is more water vapor on cloudy days, the relative air density is smaller. However, the comparison of air pressure between winter and summer, sunny and cloudy days is usually based on human feelings, not academics. People's feeling of air pressure is determined by oxygen concentration, so it is more appropriate to discuss it here with oxygen concentration.

As for feeling sultry when the air pressure is low, it is a physiological reaction of insufficient oxygen supply caused by low atmospheric oxygen concentration.

To sum up, cloudy days are lower than sunny days and summer is lower than winter.