{"id":286842,"date":"2023-11-06T17:18:18","date_gmt":"2023-11-06T16:18:18","guid":{"rendered":"https:\/\/climatescience.press\/?p=286842"},"modified":"2023-11-06T17:18:21","modified_gmt":"2023-11-06T16:18:21","slug":"light-shaking-water","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=286842","title":{"rendered":"Light Shaking Water"},"content":{"rendered":"\n
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In an unexpected twist, researchers at the Massachusetts Institute of Technology (MIT) think they have discovered a whole new source of evaporation, and its transformative effect on liquid water could eclipse even that of heat. Light itself.<\/em><\/strong><\/p>\n\n\n\n

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From Watts Up With That?<\/a><\/p>\n\n\n\n

Guest Post by Willis Eschenbach<\/strong> [See update at end]<\/em><\/p>\n\n\n\n

From the Ministry of Settled Climate Science, I came across a most fascinating press report entitled Surprise Discovery Reveals a Whole New Source of Evaporation<\/a>. Seems that scientists have noticed that light alone can evaporate water. I always figured they knew that, it only seemed logical to me. Light strikes a water molecule and has enough energy to knock it loose from the liquid surface. I even made a graphic of it somewhere in the past, but it\u2019s lost in the mists of time.<\/p>\n\n\n\n

Seems like it wasn\u2019t known, though. Turns out there\u2019s something called the \u201cThermal Limit of Liquid Water\u201d which was believed to give the maximum evaporation rate for a given temperature and vapor pressure.<\/p>\n\n\n\n

But if the water is exposed to light, the Thermal Limit can be exceeded. And not by a little. In one study<\/a> they induced evaporation at 278% of the Thermal Limit.<\/p>\n\n\n\n

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White condensation on glass as green light evaporates a water-laden hydrogel. (Tu et al., PNAS, 2023)<\/em><\/figcaption><\/figure>\n\n\n\n

There are a couple of big implications of this if the early experiments are verified. One is that it will make solar desalination much cheaper. Given the planet\u2019s population and current water scarcity, this is huge news.<\/p>\n\n\n\n

The other is that it\u2019s going to mess with climate science. Consider the water droplets at the top of the clouds. Normally, when water evaporates, it cools the surroundings. But if some of it is evaporating without changing temperature \u2026 it\u2019s gonna change the energy budget numbers.<\/p>\n\n\n\n

I mean, before this you could say \u201cX mass of surface water evaporated cools the surrounding by Y amount. When it condenses in the clouds it releases the latent heat and warms the cloud bases. And when the cloud evaporates, it cools the surroundings by Y amount\u201d.<\/p>\n\n\n\n

But with this new finding, both the first and last steps, the steps involving evaporation, are more complex. Now it seems that some of it evaporates without cooling the surroundings.<\/p>\n\n\n\n

Not sure what to think about all that. My first question, unanswered in the press release, is:<\/p>\n\n\n\n

Does the same hold true regarding longwave thermal radiation? My guess is no, but who knows?<\/p>\n\n\n\n

My best to all,<\/p>\n\n\n\n

w.<\/p>\n\n\n\n

[UPDATE<\/strong>\u2014Thanks to Johanus in the comments for pointing out that the draft version of the full paper is available here<\/a>.]<\/p>\n\n\n\n