Surprising, yet ubiquitous

Conventional wisdom has long said that heat is required in order for a fluid to evaporate, be it water in a pond, fuel in an engine, or sauce reducing in a pan. While this remains true, Gang Chen’s groundbreaking research reveals that it is not the only truth. He has discovered that photons on the surface of a cluster of water molecules can be absorbed by cleaving from it, resulting in a measurable decrease in water weight. Furthermore, the effect appears to be stronger under green light, which is also where the solar spectrum is strongest and where water is least absorbing. According to Dr. Chen, “I believe this process is ubiquitous in nature, in clouds and fogs, on land and ocean surfaces, and in plant transpiration. It is surprising that this effect has not been discovered before.”

Because of the photomolecular effect’s role in water evaporation and condensation, Dr. Chen believes that this discovery should lead to a revision of current climate models. His Bose Fellow grant will enable him to further study the impact of this effect on clouds—which, of course, are composed of water droplets—particularly how their absorption of sunlight contributes to cloud thinning. “Clouds are integral to the water cycle, which supports life one earth,” he says, “and we know that water in the atmosphere is a major contributor to global warming, so being able to calculate this impact is very important.”

“No one believes us.”

The challenges facing Dr. Chen are many. The biggest is perhaps the most basic. “No one believes us yet,” he says. “People continue to think that evaporation requires heat. We have to convince them that what we have discovered is true.” Getting peers on board is essential because Dr. Chen will have to collaborate with experts in the areas of climate and global warming, which are outside his expertise. Still, scientific colleagues will likely be more inclined to support this work than traditional funders would be. Typically, foundations require preliminary data, but, as Dr. Chen notes, “We don’t even know how to mathematically describe this effect. We have hypotheses, but to apply this to the current model we have to be able to quantitatively describe how light is actually absorbed at the surface. This will help us to understand how much solar energy must be absorbed for clouds to dissipate into the atmosphere.”

Looking at clouds from both sides now

While this research may one day help to better predict weather and the effects of global warming and earth’s water cycle, Dr. Chen is clear that he is focused on learning more about this phenomenon, rather than on applications of that knowledge. In the first year of the three-year grant, he hopes to simulate in a fog chamber—by injecting droplets of water into the chamber, shining light on it, and measuring the evaporation rates—what he observed in the lab. “Eventually, I might want to study the effect in actual clouds in the sky,” he says.

The impact of this discovery on Dr. Chen promises to be huge. He is giving up all his other research areas to study this new phenomenon. With no prospects for funding from other sources, Dr. Chen is grateful for the Bose Fellow award, which, in his words, “will lead to more excitement and collaboration. I will learn what people have been doing in the area of climate. But we still need to convince people. We have some preliminary data but we don’t know how to model it yet. So we need to do that work first—and thanks to the Bose funding, I can.”