Condensation on outside of glasses

In summary, the conversation discusses the appearance of water droplets on the outside of a cold glass of water on a warm day. The concept of partial pressure and saturated vapour pressure is mentioned, and it is suggested to look up the dew point and relative humidity for a better understanding. The explanation is given that warm air can hold more water vapor than cold air, so when the air is cooled by the cold glass, it reaches a point where it cannot hold as much water and the excess condenses onto the glass. The definition of dew point is also mentioned, which is when the air is saturated with water vapor. The connection between dew point and capacity of air to hold moisture is explained, and it is clarified that if the dew point is
  • #1
mememe653
6
0
On a warm day, why do droplets of water appear on the outside of a cold glass of water? I don't really understand partial pressure and saturated vapour pressure, but I know it has something to do with this. Like when partial pressure = SVP, the water will boil, but at what point will water vapour condense...?
 
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  • #2
You would want to look up dew point.
And relative humidity is applicable also.
Come back with a few more questions if you need to.
 
  • #3
My understanding is that warm air can hold more water vapor than cold air. So if you have warm air with a lot of water vapor getting cooled (perhaps by a cold glass) to a temperature where it cannot hold as much water, it has to dump the excess water out. Onto the glass, in this case.
 
  • #4
I agree with Lsos.
But I always thought that the cold glass would cool down the gas (air) around it into liquid form, thus creating the water droplets on the outside of the glass.
 
  • #5
Since your house is always at room temperature, this has nothing to do with the capacity of the air to hold moisture. It is all about humidity. When the air is more humid and the dew point is above the surface temperature of the glass, dew will form. That's basically the definition of "dew point".
 
  • #6
russ_watters said:
Since your house is always at room temperature, this has nothing to do with the capacity of the air to hold moisture. It is all about humidity. When the air is more humid and the dew point is above the surface temperature of the glass, dew will form. That's basically the definition of "dew point".

Isn't dew point the point where air cannot hold any more moisture (water-to-air saturation temperature)...in which case it has everything to do with the capacity of the air to hold moisture?

I just glanced at the Wikipedia explanation at dew point and it seems to exactly fit what I described...

If the dew point is below the room temperature in your house, for example, it means that the air CAN hold more water. However, if the cold glass cools the air to below that dew point, then that colder air CANNOT hold more water. Indeed, it already has too much, and it gets rid of it.
 
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  • #7
Lsos said:
Isn't dew point the point where air cannot hold any more moisture (water-to-air saturation temperature)...in which case it has everything to do with the capacity of the air to hold moisture?
Yes, your explanation is correct, but I was trying to convey to the OP that his first sentence, which starts off "On a warm day..." was off the mark. I probably could have done it better.
 

Related to Condensation on outside of glasses

1. Why do glasses get condensation on the outside?

Condensation occurs on the outside of glasses when warm, humid air comes into contact with the cooler surface of the glass. This causes the water vapor in the air to condense into liquid droplets on the glass surface.

2. Does the type of glass affect condensation?

Yes, the type of glass can affect condensation. Double-walled or insulated glasses are less likely to get condensation on the outside because they have a layer of air between the two glass walls that acts as insulation. This prevents the outside of the glass from getting too cold and causing condensation.

3. How can I prevent condensation on the outside of my glasses?

To prevent condensation on the outside of glasses, you can try using glasses with double walls or insulation. You can also try wiping the outside of the glass with a dry cloth to remove any excess moisture. Additionally, keeping the room well-ventilated and reducing humidity levels can also help prevent condensation on glasses.

4. Is condensation on the outside of glasses harmful?

No, condensation on the outside of glasses is not harmful. It is simply a natural process that occurs when warm, humid air comes into contact with a cooler surface. However, if left for extended periods of time, the moisture from the condensation can cause damage to wooden surfaces or cause mold to grow.

5. Can condensation on the outside of glasses be a sign of a larger problem?

In most cases, condensation on the outside of glasses is not a sign of a larger problem. However, if you notice excessive condensation or if it occurs on a regular basis, it may be a sign of high humidity levels in your home which could lead to issues such as mold or mildew growth. In this case, it is important to address the humidity issue to prevent any potential problems.

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