Why is the water vapor content in the air higher in summer than in winter?

Affected by temperature, surface water evaporates much more in summer than in winter.

The water vapor content in the air is directly related to the atmospheric temperature. The higher the temperature, the greater the solubility of water vapor and the higher its content. Therefore, the temperature in summer and low latitudes is higher, so the water vapor content is also higher.

Water can be used as a solvent or a solute, and so can air. The water vapor in the air is the solute, and the air is the solvent.

Related notes

The density of water vapor is approximately 0.622 times that of dry air at the same temperature and pressure, that is, the density of water vapor is always smaller than the density of dry air. The gas constant (Rw) of water vapor is 461 Joules/kg·Kelvin, and the specific heat at constant volume (Cv) is equal to 716 Joules/kg·Kelvin. Water vapor in the atmosphere comes from the evaporation and transpiration of the underlying surface, and its content varies from time to time and place. Calculated by volume, its range ranges from 0 to 4%. It can reach more than 4% in tropical rainy areas, and almost 4% in cold and dry areas. Close to zero.

The vertical distribution is mainly concentrated in the air layer 2-3 kilometers above the ground. The higher the altitude, the less water vapor. Water vapor is the only component in the atmosphere that can undergo phase changes, so it is extremely important in weather changes. Water vapor can strongly absorb ground radiation, and can also emit long-wave radiation. It continuously releases or absorbs heat during the change of water phase, so it has a great influence on the temperature of the ground and air.