Transpiration is a process in which the plants evaporate water. It occurs in the leaves when stomata are open during the passing of CO₂ and O₂ and that process is called photosynthesis. The process is affected by environmental factors like light, temperature, humidity, and wind and soil water.

Diffusion is the phenomenon of the constant thermal motion of atoms, molecules, and particles, and results in material moving from areas of high to low concentration. Thus the end result of diffusion would be a constant concentration, throughout space, of each of the components in the environment.