Humidity is the measurement of the amount of water vapor in the air at a given time. Relative Humidity (RH) is defined as “the ratio of the partial pressure of water vapor to the equilibrium vapor pressure of water at a given temperature.” For example, 50% RH equals to 50% of the max water vapor capacity of the air at a given temperature.
Humidity is essential for plants to undergo photosynthesis. If a plant loses too much water the stomata may close, which forces photosynthesis to pause because no carbon dioxide can be absorbed and no oxygen can be released.
In the case of Cannabis, the ideal relative humidity level depends on the strain of cannabis and also on the plant’s environment.