Condensation explained

[aermale]

No problem. Your experience is exactly what's needed here.
So, if I'm in the warm, humid southern us, and a cold front pushes cold, dry air into our atmosphere, does the house air stay at the same moisture level? That's what I'm thinking. The moisture rich, warm air indoors would be carried outside in the bird and humidity released via condensation, once cooled. Correct me if I'm wrong though.

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[Monte55]

To measure relative humidity we used to use a sling phycrometer . It had two mecury thermometers in it. One had a sock on it that we would wet with water. Now we would swing it around in the air for about a minute until the temperatures would stabilize. We would read both temps and refer to a chart. Naturally the one with the wet sock would cool down because of the evaporation of the water. The drier the air, the colder the reading. The other would just read ambient temp. This would get you close to the RH but to be very accurate, we needed to know the atmospheric pressure.

 

[aermale]

I put the glass in the freezer. From the cupboard, there was no noticeable moisture. After a few minutes in the freezer, there appeared to be a little frozen condensate(frost). I pulled it out and noticed much more condensation forming than the thawing alone. I assume its the frozen condensation thawing, plus the moisture from the air surrounding the glass?

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[Monte55]

[QUOTEI'm aermale, post: 1048948, member: 78328"]Thinking of relative humidity as a ratio, that would be correct. The 17 ° air outside can hold less moisture, therefore itsdegrees 78% capacity, compared to the warm air, which is only at 20% capacity.

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Maybe I'm not reading this correctly but it makes no sense to me. Water is in a compressed state. It can't be compressed any further. Now, most know water will boil at 212 degrees F at sea level. That is to say the liquid will change from liquid to a vapor. In higher elevations, water will boil at a lower temperature. Less pressure on the water. So, if less pressure makes water boil at a lower temperatur , it only makes sense that higher pressure will require a higher temperature to make water boil. That is why we have pressurized cooling systems on cars. The higher the pressure, the higher the temperature has to be to have a boil over. Let's go the other way. If I reduce the pressure, I can boil water at much lower temperatures. When I work or refrigeration systems, I have to remove as much moisture from system as possible. Moisture is very bad for these systems. Let's say I'm trying to get moisture out of a system. I could heat the entire system up to above the boiling point for the altitude that I am at. Can't do that. I could shoot the system into space which is basically a vacuum to remove the moisture . That would
cost a lot and take some time. So, I use my vacuum pump reducing the pressure in the system so much, I can get water to boil at below 0 degrees F. What does this have to do with the humidity talk. A LOT.

 

[Richard R]

I was hoping people would chime in with some strategy to defeat this concept. Its really cold outside and my batteries are charged. I want to play....

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Try warming the bird back up in stages. If you have an attached garage, it will likely be warmer than outside, but cooler and drier than in the house. Leave it ther for a bit hen move it in. Again, fog on you glass is a good indicator.

 

[Monte55]

If you want to reduce the chance of moisture forming on a cold object coming inside to warm air...put object in a plastic bag....squeeze out as much air as possible and seal the bag. A kitchen trash bag will do. I doubt this is really a big problem unless the temps and humidity are at extremes. If you do bring one in from cold weather. ..let it breathe. Don't put it into a closed case immediately.

 

[Erised]

If you want to reduce the chance of moisture forming on a cold object coming inside to warm air...put object in a plastic bag....squeeze out as much air as possible and seal the bag. A kitchen trash bag will do. I doubt this is really a big problem unless the temps and humidity are at extremes. If you do bring one in from cold weather. ..let it breathe. Don't put it into a closed case immediately.

That's what I do when coming in from the cold. Being Canadian and wanting to fly I have to go out in the cold. My condensation issue is coming in from minuses to warm home with 43%RH. I place the bird in a plastic bag leave the warm battery in and seal it outside and bring it in and leave to warm to room temp, the bag gets wet but not the bird. I make sure the craft in dry then store it in it's case with a silica bag. If it's not that cold I just leave the warm battery in the craft to prevent moist air from entering the craft and the heat from the battery helps dry the craft. I see it as a pair of glasses, when I go out in the cold no fogging but coming indoors they fog up big time. The out side air is so dry it can absorb lots of humidity without causing water droplets. Up north when all is frozen over it can get as dry as the Sahara desert.

 

[Monte55]

That's what I do when coming in from the cold. Being Canadian and wanting to fly I have to go out in the cold. My condensation issue is coming in from minuses to warm home with 43%RH. I place the bird in a plastic bag leave the warm battery in and seal it outside and bring it in and leave to warm to room temp, the bag gets wet but not the bird. I make sure the craft in dry then store it in it's case with a silica bag. If it's not that cold I just leave the warm battery in the craft to prevent moist air from entering the craft and the heat from the battery helps dry the craft. I see it as a pair of glasses, when I go out in the cold no fogging but coming indoors they fog up big time. The out side air is so dry it can absorb lots of humidity without causing water droplets. Up north when all is frozen over it can get as dry as the Sahara desert.

Then you understand the process....If you were a dog...I would say "you a good boy""

 

[Erised]

The cold air is so dry that after going indoors and condensing my glasses then going back out with foggy glasses they clear up (dry) within a minute or so in the cold dry air.