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Light can make water evaporate without heat

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Re: Light can make water evaporate without heat

#191

Post by sheepscreek »

m463 wrote: post #80
elil17 wrote: post #44

Earlier quoted context omitted.

Thermodynamics and evaporation are my day job and I think most other explanations here are missing the point. Evaporation normally occurs when individual water molecules have enough thermal energy to break their intermolecular bonds, leaving the bulk liquid and entering the air. In this case, they found strong evidence that water molecules were being removed in groups of several water molecules. Because intermolecula…

> I'm not really sure whether to even call it evaporation I can't help but think of ultrasonic humidifiers/misters, which use vibration to do evaporation-adjacent kinds of things. I also wonder if specific wavelengths of light are involved (sort of how 2.4ghz microwaves work on water)

This was also my first thought! And they seem to cool the air nearby. The above explanation makes sense (where bonds are broken in the air).

Re: Light can make water evaporate without heat

#192

Post by sheepscreek »

dr_dshiv wrote: post #158
m463 wrote: post #80

Earlier quoted context omitted.

> I'm not really sure whether to even call it evaporation I can't help but think of ultrasonic humidifiers/misters, which use vibration to do evaporation-adjacent kinds of things. I also wonder if specific wavelengths of light are involved (sort of how 2.4ghz microwaves work on water)

Cue “burning” salt water video: https://youtu.be/e8utkoK2DhA?si=t2cvuu4V-hFKFjM8 I’m still blown away that radio frequencies can dissociate hydrogen without an electrode. I haven’t read a good explanation of the phenomenon.

Ever heard of a Plasma gun? Or pressurized water cutting? Heck Lasers do the same thing.

In every case, it’s really a collision between different particles at various energy levels, leading to different results.

Take an extremely fast neutron and collide it with an atom, and you could alter the chemical composition of the atom/end up with a different element (basic principle of breeder reactors). Fascinating stuff.

Re: Light can make water evaporate without heat

#193

Post by Sparkyte »

MagicMoonlight wrote: post #156
viraptor wrote: post #154

Earlier quoted context omitted.

One which can get absorbed by a single molecule individually as opposed to sound which has to affect large groups of them, increasing movement / heat.

Sound is movement, it’s not a particle. It’s your way of sensing stuff smashing together by feeling the ripple that comes off it

Both kinetic energy.

Re: Light can make water evaporate without heat

#194

Post by _nalply »

dr_dshiv wrote: post #189
_nalply wrote: post #186

Earlier quoted context omitted.

I wonder how strong the radiation was. If strong enough it dissociates and then by burning it gives back the energy... Looks like a fake perpetuum mobile...

Yeah, obviously strong enough to make the energy balance. But still awesome.

Yes it's awesomeness reminds me of the Tcherenkoff light I once saw with my own eyes. It was a deep pool of a test reactor and I even asked the guide if I am allowed to put my index finger into the water. It was warm. I looked long and deep at the fascinating white-blue light in the water.

It is so awesome that no public relations work is needed. The thing speaks for itself and is so convincing.

Re: Light can make water evaporate without heat

#195

Post by smolder »

foota wrote: post #93
elil17 wrote: post #44

Earlier quoted context omitted.

Thermodynamics and evaporation are my day job and I think most other explanations here are missing the point. Evaporation normally occurs when individual water molecules have enough thermal energy to break their intermolecular bonds, leaving the bulk liquid and entering the air. In this case, they found strong evidence that water molecules were being removed in groups of several water molecules. Because intermolecula…

What happens if the air is saturated? Does the molecule clump just settle back down where it came from, or would it stay suspended somehow in the air (mist?)? Alternatively, I wonder if this could be used as a super swamp cooler, I'm picture water dripping or flowing from a tube, a laser causing it to "burst apart", and then the droplets formed rapidly cooling the surroundings due to their surface area.

It seems possible we could improve swamp cooling with this, as with desalination, though in general you want to avoid putting energy into the system, I think. Powering a laser might overcome the benefits... unless you shot lasers in from outside? Even so, it might be best to use [filtered?] natural light for such a system.

Re: Light can make water evaporate without heat

#197

Post by MayeulC »

_nalply wrote: post #184
austin-cheney wrote: post #152

Earlier quoted context omitted.

No. Plants reflect green to balance luminosity extremes. Green is by far the most luminous color in the visible spectrum with dark purple being the least luminous. Plants that reflect purple absorb the most visible light and can produce the most sugars. Most plants must undergo a chemical transition to shift from production to dark mode and by choosing to reflect green maximum energy production is sacrificed for inte…

> most luminous color What does luminous mean exactly in this context? I know that our eyes are most sensitive to green. For example a green LED needs less power to seem as bright as a red LED. But our eyes don't matter in this subject. So I am scratching my head about what you mean that green is the most luminous color?

I think this is the color (wavelength) that corresponds to the sun's emissivity peak (irradiance in W/m²).

The fact that our eyes are most sensitive to green is probably not an accident, but is it due to the color of leaves, or is it due to sunlight?

Re: Light can make water evaporate without heat

#198

Post by araes »

m463 wrote: post #80
elil17 wrote: post #44

Earlier quoted context omitted.

Thermodynamics and evaporation are my day job and I think most other explanations here are missing the point. Evaporation normally occurs when individual water molecules have enough thermal energy to break their intermolecular bonds, leaving the bulk liquid and entering the air. In this case, they found strong evidence that water molecules were being removed in groups of several water molecules. Because intermolecula…

> I'm not really sure whether to even call it evaporation I can't help but think of ultrasonic humidifiers/misters, which use vibration to do evaporation-adjacent kinds of things. I also wonder if specific wavelengths of light are involved (sort of how 2.4ghz microwaves work on water)

I suspect you're correct, at least partially.

My personal suspicion is that the light waves are hitting the extremely diffuse binder material and then ejecting the water light a billiard ball or a solar sail effect. It may have a resonance (vibration) with the binder structure. See below image for example of binder material.

https://upload.wikimedia.org/wikipedia/commons/d/d3/Short-pe...

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