Humidity is a term meteorologists use to indicate how much water is in the air. It is determined by comparing the actual amount of water in the air to what it can hold. Humidity is written as a percentage. During the day the humidity in a tropical rainforest measures about 80%. At night the humidity is even higher at 95%.
The understory, or lower canopy, consists of 60 foot trees. This layer is made up of the trunks of canopy trees, shrubs, plants and small trees. There is little air movement. As a result the humidity is constantly high. This level is in constant shade.
In an average year the climate in a tropical rain forest is very humid because of all the rainfall. A tropical rainforest gets about 150 cm of rain per year. It gets lots of rain because it is very hot and wet in rain forests. The hotter the air, the more water vapor it can hold. It rains usually about 1/8 of an inch per day.