greenhouse effect A glass enclosure can pump itself to higher energy density compared to its environment by one way transfer of energy. A light photon passes through glass wall of the container. The content of the enclosure absorbs the photon This process heats up the contents of the enclosure. The heated contents re- emit photons with wavelength in infrared region. These photons however are reflected by glass walls back into the enclosure. This results in the temperature inside the greenhouse being higher than its environment.