Final answer:
The humidity holding capacity of the air is greater on a hotter day and lower on a colder day due to the effects of temperature on the saturation vapor pressure.
Step-by-step explanation:
The amount of water vapor capacity in the air, which is often referred to as the humidity holding capacity of the air, is greater on a hotter day and lower on a colder day. This is because warm air can contain a higher volume of water vapor than cold air. On hot, dry days, the evaporation of sweat from the skin effectively cools the body. However, on humid days, the air contains a higher concentration of water vapor, which reduces the rate of evaporation from the skin's surface, making it feel hotter.
When discussing humidity, we are actually referring to relative humidity, which measures the amount of water vapor present in the air compared to the maximum amount of water vapor the air can theoretically hold at that temperature. At 100% relative humidity, the air has reached its saturation point, meaning the partial pressure of water vapor is equal to the vapor pressure, and thus evaporation is inhibited. Temperature plays a significant role here, as it affects the saturation vapor pressure and hence the capacity of air to carry more or less water vapor.