The lighter it is the faster the rate of transpiration. The stomata opens when it is light which means that more water is lost.
Higher the temperature the faster the rate of transpiration. Warmer water molecules evaporate faster so transpiration increases.
Lower the humidity the faster the rate of transpiration. The water potential gradient between the leaf and air inceases.
More water faster transpiration gradient. Lots of movement blows water from the stomata . This increases the water potential gradient.