Biology

Light

Plants transpire more rapidly in the light than in the dark. This is largely because light stimulates the opening of the stomata. Light also speeds up transpiration by warming the leaf. And also increases the rate of transpiration.

Temperature

Plants transpire more rapidly at higher temperatures because water evaporates more rapidly as the temperature rises. At 30°C, a leaf may transpire three times as fast as it does at20C. A rise in temperature increases kinetic energy, this increase movement of water molecules increases the rate of evaporation of water., decreases humidity of air outside leaf.

Both changes lead to increase in transpiration rate.

Humidity

The rate of diffusion of any substance increases as the difference in concentration of the substances in the two regions increases.When the surrounding air is dry, diffusion of water out of the leaf goes on more rapidly.

low humidity increases the rate of transpiration.

Air movement

increases air movement increases the rate of transpiratuiona as it moves the saturates air from around the leaf so the gradient is steeper