Light can make water evaporate without heat

Post by iamgopal » Fri, Nov 03, 2023, 4:01 PM UTC

SkyPuncher wrote: post #179

malfist wrote: post #95

Earlier quoted context omitted.

Maybe, but evaporation is critical for plants. They don't have a heart to pump blood and supply nutrients, they have to rely on evaporation to move nutrients from the roots up

Plants rely on on capillary action to bring water up: https://www.usgs.gov/special-topics/water-science-school/sci... . There's probably some aspect of evaporation, but the density of water is much, much higher when it's kept in liquid form.

Post by _nalply » Fri, Nov 03, 2023, 5:46 PM UTC

austin-cheney wrote: post #152

montjoy wrote: post #71

> The researchers found that the effect varied with color and peaked at a particular wavelength of green light. I wonder if this affects photosynthesis in any way? IIRC plants are green because chlorophyll does not absorb that color. Maybe that’s partially because green light induces too much evaporation?

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…

Post by _nalply » Fri, Nov 03, 2023, 8:25 PM UTC

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.

Post by mrguyorama » Fri, Nov 03, 2023, 9:24 PM UTC

bmacho wrote: post #161

Sparkyte wrote: post #148

Earlier quoted context omitted.

And what type of energy is light?

Imagine a material, or a passive device, that can evaporate a glass of water fast, using only the heat of the environment, as the energy source. That is possible, and would be huge.

Post by buildartefact » Fri, Nov 03, 2023, 11:06 PM UTC

austin-cheney wrote: post #187

_nalply wrote: post #184

Earlier quoted context omitted.

> 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?

Here is the math used by W3C for computing acceptable contrast: https://www.w3.org/TR/WCAG20/#relativeluminancedef I suspect luminosity to mean percentage of brightness for a given frequency from a total light source assuming white light. For a more precise definition I would look to physics.