Evaporation in 100% relative humidity

In summary, the conversation discusses the process of water evaporation in relation to temperature and humidity. It is mentioned that at 100% humidity, water cannot evaporate, but there is some uncertainty about this. The question is also raised about the effect of a warmer water surface on evaporation and how it relates to humidity. Finally, the conversation touches on the relationship between humidity and the rate of evaporation over time.
  • #1
classicphysic
3
0
hello guys

if the water surface is at same temp as air above, and humidity is 100%, do any wataer molecules leave their liquid state to become vapour ie evaporate?

I couldn't remember what professor said exactly, so i checked up on internet and it says

water can't evaporate at 100% relatve humidity. But I vaguely remember it can..

I am not so sure so can anyone clarify this please?

What happen to net evaporation ie positive or zero. if the water surface is warmer than the air above at 100 humidity?

thank you

also, if the humidity is 50% at 20 degrees, what happen to evaporation rate as funtion of time? (two critical processes invovled)
 
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  • #2
Not all molecules in an ensemble will carry the same energy. Temperature only specifies the average. More energetic molecules in the water will evaporate, but at the same time the less energetic molecules in the air will condense. If the air is saturated at the water's temperature then these two processes will be in equilibrium.
If the water is warmer then evaporation will exceed condensation, locally raising the temperature of the air. As the warmed air mixes with the cooler air around, some will recondense, forming a mist.
As time passes, evaporation robs the water of its more energetic molecules, lowering the average energy (and hence temperature) of what remains.
 

1. What is evaporation in 100% relative humidity?

Evaporation in 100% relative humidity refers to the process of water molecules transitioning from a liquid state to a gas state, even when the surrounding air is already saturated with water vapor.

2. Can evaporation occur in 100% relative humidity?

Yes, evaporation can still occur in 100% relative humidity because the process of evaporation is dependent on the difference in water vapor concentration between the surface of the liquid and the surrounding air, not just the overall humidity level.

3. How does evaporation work in 100% relative humidity?

In 100% relative humidity, the air is already saturated with water vapor, so the rate of evaporation will be very slow. However, as long as there is a difference in concentration between the liquid and the air, evaporation will still occur.

4. What factors affect evaporation in 100% relative humidity?

The main factor that affects evaporation in 100% relative humidity is the temperature. Higher temperatures will increase the rate of evaporation, while lower temperatures will decrease it. Other factors include air movement, surface area of the liquid, and the type of liquid being evaporated.

5. Why is evaporation in 100% relative humidity important?

Even though evaporation in 100% relative humidity may be slower, it is still an important process in the water cycle. It helps regulate the Earth's temperature, contributes to cloud formation, and is crucial for the survival of plants and animals. Additionally, it plays a role in the purification of water as it removes impurities through the process of evaporation and condensation.

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