Movement of moist air masses also transports water from the oceans to the land areas across our entire planet. At any temperature, there is a limit to the amount of water vapor that the atmosphere can contain. Once the water vapor limit is reached, the air is said to be saturated . An attempt to add more water vapor to saturated air will produce condensation . As the temperature of the atmosphere increases, the saturation limit also increases.
Warm air can therefore contain more water vapor than cool air without condensation.
Add ice cubes to a glass of water and observe the formation of condensation. Prove to yourself that there is water vapor in our atmosphere even if it cannot be seen. Usually the humidity is highest at night when the temperature is cool and the water vapor saturation limit is low, and the humidity is lowest in the afternoon when the temperatures and corresponding saturation limits are high. In desert areas where there is very little water vapor in the atmosphere, the humidity is generally low. In tropical areas where there is much water vapor in the air, the humidity is typically high.