How can water evaporate from a pool in the summer when it is supposed to evaporate at 100°C ?
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Water bottle at 100 degree Celsius. It can evaporate at all temperatures over 0 Kelvin, although the rates of evaporation will differ at different temperatures.
Water evaporates at any temperature above freezing. The hotter it is, the faster it does so.
It boils at 100 but evaporates at any temperature. The water is not all at the exact same temperature. The molecules zip around and crash into each other constantly. So each molecule can be far bellow zero in one moment and then far above boiling in another moment as other molecules have bumped into it. This means that at any point in time there are lots of molecules at the surface of the water which have a higher then boiling temperature. And these will be able to escape into the atmosphere. This is called evaporation. The higher the temperature the faster the evaporation.
It *boils* at 100C. This is a different process.
When a liquid is boiling the entire mass of liquid is changing phase, all molecules have enough energy to make the phase transition into a gas.
Below that temperature, molecules near the surface can still jump for it when they get hit just right. It’s a much slower process that occurs only at the surface and only when the air is suitably dry.
The molecules at the surface wander off and can’t find their way back, slowly converting the whole puddle into vapor.
If it’s too humid it won’t happen. Boiling forces the liquid into the gas phase no matter what the humidity level is.
Boiling != evaporation. If that was the case clothes wouldn’t dry unless they were above 100C which isn’t the case. Water is always evaporating
Water can be dissolved in the air, just like salt can be dissolved in water. The melting point of salt is 800°C, but there’s still salt in the liquid ocean. Humidity is just the measure of how much of the air’s capacity to hold water is filled. Heating up or stirring air will speed up the process of water drying up, just like heating up water will speed up the dissolving of salt. It’s simply water molecules from the surface of the water sticking to the air molecules by random chance and getting dislodged from the rest of the water and being suspended in the air. When you cool down the solution, whether it’s air or water, the process of the solute coming out of solution is called precipitation. With salt, you can even form crystals this way, and if you get the air cold enough, you can form crystals of water too called snow.
The reason is that water actually boils at 100 and evaporate at any temperature.
That’s boiling is fast process while evaporation is slow process as compared to boiling.
Adding to it,On a summer day it is hot and humidity is very low which is favourable for evaporation.
It depends on air pressure. If a high pressure is in the area, it is harder to evaporate water. If a low pressure is in the area, the water evaporates faster.
The temperature of a material is an average.
The molecules actually have a wide range of temperatures. And each individual molecules temperature will fluctuate as it’s neighbors bump into it. Sometimes sending it off faster (hotter) sometimes slowing down (cooler).
So in a puddle of water at 50c, most will just chill. But some small fraction (say 0.1%) is actually bumped hard enough to leave. Sometimes this molecule is near the edge so it gets pumped free entirely. Sometimes it’s in the middle so it simply bumps into another and slows back down.
So this means that it can slowly evaporate even at 50c.
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