These approximations were supported by the unidirectional nature of the relationship between both volumes. The climate of the air over the crop affected the climate of foliage entrapped air but this was not true in the reverse direction, since the volume of free air was much larger than the volume of entrapped air.
Adicionalmente, este enfoque se justifica porque el modelo físico indica que la relación es unidireccional, el clima del aire sobre el cultivo afecta el microclima del follaje, pero, como el volumen de aire encerrado es mucho menor que el volumen total del invernadero, la influencia en sentido inverso es despreciable.