Cloud Absorption and Fog Heating by Visible Light due to Photomolecular Effect

Despite that the bulk water is nearly transparent to visible light, we recently discovered that visible light can be absorbed at water-air interface via a process we call the photomolecular effect, in which a photon can cleave off water molecular clusters. We hypothesize that this effect is behind the experimental observation of anomalously high clouds absorption, which has been controversial for nearly 80 years since the large cloud absorption cannot be explained based on bulk water optical constants. We show experimentally that the temperature of a dense thin fog increases significantly under LEDs of multiple wavelengths in the visible spectrum with intensity comparable to solar radiation, peaking at the 520 nm (green) where bulk water absorbs least. Green laser irradiation of the fog further confirms heating effect. Monte Carlo further supports the photomolecular absorption mechanism can explain the anomalous cloud absorption. Our study suggests that photomolecular effect can highly influence the global climates.