How does humidity affect transpiration?

Humidity has a significant impact on transpiration rates. High humidity reduces the rate of transpiration because the concentration gradient between the water vapor inside the leaf and the surrounding air is smaller, resulting in less driving force for water to evaporate. Conversely, low humidity increases the rate of transpiration because the air is drier, creating a larger concentration gradient and enhancing the movement of water vapor from the plant to the atmosphere. Changes in humidity levels can therefore influence a plant’s water loss and overall water balance.