Describe the factors which affect the rate of transpiration.

There are 4 factors which affect transpiration: Temperature, Light intensity, Humidity and Wind speed.As the temperature increases, the rate of evaporation and diffusion increases as the particles have more energy.Light intensity affects the rate of transpiration because the stomata can be opened or closed to allow for diffusion of CO2 from the environment and therefore water vapour can be lost through these gaps. This normally happens during the day to maximize photosynthesis rates but it can occur at different times depending on the adaptation of the plant species.As humidity increases, the level of transpiration decreases as there is less of a concentration gradient meaning less water escapes from the leaves.Wind speed is linked to humidity in that as the wind speed increases the levels of transpiration also increase because the wind blows the water away from the leaves giving a larger concentration gradients for water to diffuse.