Q: Why does water evaporate? If you leave a glass of water in

>>7694013
nicecakes

It's more energetically favourable for water to exist in a gaseous form than a liquid form. Another mystery solved.

>>7694047
that depends totally on temperature, pressure, etc and cannot be generalized in that way

because there is less water in the air, water will evaporate in order to equlibrate

>>7694013
>it will not boil, so it is not turning to vapor
Nope. Boiling means bringing the average temperature of the water to its boiling point.
That's the average. Individual molecules can still randomly achieve enough energy to become vapor, and will continue to do so until the air becomes saturated.

I think that its some molecules have more energy than others (ie they have differ and when it gets past a point these change to a gas.

There's a cup of very salty water in my garage that's been standing there for years. It dripped out of a bag of salt used for our sidewalks. It's kind of strange to see it there, never evaporating.

>>7694080
read this, op
then read it again
it's rare to find this kind of knowledge on sci

>>7694013
Boiling is basically a state in which water evaporates with its entire volume, while in lower temperatures only the water on the surface does.

>>7694080
This is the right answer

The earth is continually being bombarded by solar particles. It is these particles that strip away the individual atoms of water. The proof of this is Mars. Luckily we have increased levels of co2 in the upper atmosphere increasing atmoospheric density and preventing OP's cup of water escaping. This answers the question and tells you why global warming causes more rain.

>>7694190
water evaporates if sealed off from solar particles.

water will evaporate as long as there remains a concentration gradient for water molecules to move along. The interesting point to note is that when these molecules move into the air there is a fixed amount that air at a certain temperature and pressure can hold. This is called humidity and more useful is relative humidity. 50% RH means the air is holding 50% of the maximum water vapour it can hold etc.
No evaporation occurs at 100%RH.

>>7694080
For some reason this reminds me of that scene in the martian where he feels the condensate on the plastic in that tiny room. Since this is a closed system, wouldn't the air be considered "saturated" if it's condensating on the walls? And if so, how can the water continue to evaporate off the plants if the room is already saturated? The plants need evaporation to function, but the tiny room seems close enough to equilibrium that it shouldn't continue with it's water cycle. I know it's just a scifi movie but greenhouses do the same shit. How are all the plants not dying?

>>7694208
havent seen movie but possibly local temperature gradients? surrounding air closer to objects is colder and water condenses out. Believe having a site to nucleate on also encourages condensation. Similar thing happens in a warm house in winter... condensation on the cold window panes but not on any of the other surfaces.

>>7694208
They take in the vapor in the air through their stomata

>>7694208
Why would plants need evaporation to function? Humidity is close to 100% year round in rain forests at ground level, and the plants there do just fine.

>>7694229
https://www.youtube.com/watch?v=BickMFHAZR0
Not sure if this applies to all plants, but if the air is saturated and no evaporation can occur, then how can plants maintain their large pressure differential?

>>7694047

I would much rather be a gas, and that's certainly energetically favourable for me. Why am I not a gas?

High energy neutrinos from distant supernovae will occasionally interact with the water, giving one molecule enough energy to leave the glass. Eventually all of the water molecules (H2Os or H2GOes as I like to call them) will be "knocked" out of the glass.

>>7694178
Technically boiling is the phase change that happens when the vapour pressure to a liquid is equal or greater than the atmospheric pressure.

>>7694208
If the temperature of a surface is lower than that of the air, water can condense on the surface without the air being at 100% humidity because the air touching the surface gets colder and is able to hold less water

>>7694062
Its more energetically favourable for water to exist in a gaseous form than a liquid form at standard temperature and pressure, the way it was fucking described. Another mystery solved.

>>7694047
That's not why, dumbnuts. It's influenced by the high energy environment. So it actually jumps to a higher energy state. Not a lower one.

Dark energy particles pass right through the earth up through the bottom of your glass. occasionally one collides with an atom of water and lifts it out.

>>7694279
Because you're a faggot and as such you have a very high boiling point.

>>7694080
Dingdingding we have a winner. This is the answer you seek.

>>7694080
This. At room temperature the molecules on the surface of the water are vaporizing. If you bring the liquid to boiling, the molecules within the liquid beneath the surface also vaporize, hence why you see bubbles.

>>7694013
magicks, not to be confused with magic which is not real

>>7694013
>in a room at room temperature forever it will not boil
tell that to the water when the Sun expands and boils it long before forever

>>7694013
Richard Feynman gave an incredibly lucid explanation of this process. You should read the lectures. OR... "6 easy pieces". That is basically an abridged version of the lecture that only reveals parts of the lectures pop-sci fags can understand.

>>7694013
>>7694080
To enrich this answer, water has a small but non-negligible vapour pressure at room temperature, and thus will evaporate until the environment surrounding it achieves a partial pressure of water that matches this vapour pressure, at which point the chemical potential of water in the gas phase and the chemical potential of water in the liquid phase are equal. This can only happen if the volume of the system is sufficiently small that the partial pressure can actually rise high enough to match the vapour pressure, which in most rooms is not the case. Hence, water left standing will often completely evaporate.

>>7694208
Differences in the local environments. There is a temperature gradient within the greenhouse due to cooling of the exterior surfaces by wind and whatnot, and thus a gradient in the vapour pressure that the local environment can support. It's warmer around the leaves so the water evaporates. The wet air then moves to the walls of the greenhouse and cools, whereupon the air becomes supersaturated with water vapour, so the water condenses on the walls until the partial pressure of water matches the vapour pressure of water at that temperature.

Atoms just moving [which they all do all the time] can cause separation of molecules.
That's decay. It's inevitable.
>Entropy

>>7694013
For the reaction
[eqn]
H_2O_{(l)} \leftrightarrows H_2O_{(g)}
[/eqn]
the reaction quotient is essentially 0, so as long as K is greater than 0 you have a reaction that will never stop occuring. This is a result of thermodynamics; in particular, the second law.

>>7694205
This is the reason why you feel hot when it's humid even though you're sweating - cooling by evaporation does not occur at 100% humidity.

>>7694205
I just wantto clarify that evaporation still occurs but there is no net movement of water.

>>7696377
I'm thinking osmotic pressure could faclitate a net movement and the excess deposits as condensation.

>>7694080
With the question answered, can an anon who never goes here normally, ask a question?

Say something the weight of a large truck gets pushed off a cliff and plummets into a large snow bank. Would the snow explode outwards more like a water landing, create a crater, or would it just leave a hole in the snow and absorb the vast majority of the landing's energy with ease? For the life of me I would think that the snow would leave a hole and no other sign of impact, but I cannot into physics.

>>7696653
The truck's gravity will pull all the snow towards it until it collapses under its weight and becomes a black hole.

>>7696653
It depends on how densely packed the snow is. If it's really loose snow then yes, the truck will simply compact the snow underneath it without doing much to the rest of the pile. If it's very dense snow then the truck will push the snow aside much like it landing on a pile of earth. It will also get rekt.

>>7697251
Thanks, anon

>>7696488
Am I right in thinking this?

>pls respond

>>7696488
Osmotic pressure exists between solutions of different concentrations separated by a semi-permeable membrane. Not relevant at all in gaseous systems.

>>7699365
Thanks. The topic was whether leaves can evaporate at 100% humidity, so it might apply.

>>7694080
I presume it's do with the mass? Does that mean 10 water molecules have a different boiling point to 20? How can water have a universal boiling point in that case?

>>7699587
The boiling point is still the same, but it just takes longer to heat up a larger mass so that the average temperature gets up to 100 degrees.

>>7696653
>>7697251
If it's REALLY fluffly snow, the air trapped in the snow will be displaced as the truck compresses the snow under it, blowing the neighboring snow away. Gotta think about what happens to the air int he snow separately from the snow itself.

>>7701504
Snow after a blizzard would be fairly compact, or is it fluffy because it is freshly fallen?

>>7702067
Depends on the temperature, air pressure, and humidity. In general though the colder it is the wetter the snow (because cold air can't hold as much water and will precipitate into larger drops), and it will weigh more and be more compact when hitting the ground.

>>7702085
Interesting. Thanks.