# Looking for references to an experiment on the evaporation rate of water in sunlight

I remember reading a long time ago about some experiments measuring evaporation rate of water in large open containers (tubs) sitting on open ground. It was a simple experiment, each day the water level would be checked and recorded. From what I remember the experiment was in the 1950's or 1960's in Israel.

Results generally made sense, the rate of loss was highest on hot sunny days, but something about the analysis lead to the conclusion that in addition to thermal effects (hot water evaporates faster than cold water) there was also a component to the evaporation rate related to the brightness of the light itself; a non-thermal or light-induced evaporation process.

I've been searching and so far come up empty-handed. I've even asked a related question in Physics SE (Rate of direct (non-thermal) photon-induced evaporation of water? ) several months ago, but so far no bites.

I can't remember where I read this, but it may have been as an anecdote in a text about either climate change or long term variability of the solar constant or the power output of the Sun.

• Non-thermal? Heat transfer — conduction, convection, radiation. Am I missing something? – Rodrigo de Azevedo Feb 27 at 23:50
• @RodrigodeAzevedo for energy to be thermalized it needs to reach some kind of local thermal equilibrium. If a photon comes in and kicks one or a few atoms out immediately for example, it would be a non-thermal process and you wouldn't use the word "heat" to discuss it. There's no temperature or change in temperature to be defined, no $\exp(-k_B T)$ Local equilibration takes time, this asks about a process that happens faster than that time. – uhoh Feb 28 at 0:43