Magnets and condensation

[IRHP]

We have a magnetic strip running all the way up and down out 2 shower doors which keeps them together. Why do I get condensation on the magnetic strips but don't get it on the frame which is aluminium or the door panels which I assume are some sort of acrylic? Is there some sort of weird scientific reason for this? I get it when I don't even have condensation on the windows. The shower cubicle has a vented skylight so It's not lack of ventilation.

 

[Jimbohorlicks]

Because they are colder ,the aluminium has a coating.

 

[IRHP]

Because they are colder ,the aluminium has a coating.

They aren't colder. If you have two items of different material in the same space over time they will be at the same temperature. They may feel colder to the touch but that's only due to thermal conductivity.

 

[Jimbohorlicks]

Sorry but I disagree. If you check your van on a cold day ,in the outside,condensation will occurr in different areas on the outer skin. This is due to the insulation and what's behind the outer skin. Similar to the magnetic strip and the aluminium frame .it only needs a change in dew point by 1 degree to result in condensation forming.

 

[Stoosal]

It may happen when there is a quick change in temperature inside the vehicle (cold night then sun warms quickly in the morning) and the different types of metal are unable to change temperature at the same rate as the air around it. The aluminium will probably change temperature faster than the magnetic strip and warmer air will condense on the colder metal if it meets the dew point. Over time the temperature of both will be the same as the surrounding air but in the period where they are at different temps it will cause condensation.

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[Skyway]

They aren't colder. If you have two items of different material in the same space over time they will be at the same temperature. They may feel colder to the touch but that's only due to thermal conductivity.

That’s wrong

 

[Ridgeway]

maybe they are water magnets

 

[IRHP]

That’s wrong

Can you explain?

 

[Skyway]

Two materials in same environment can have different temperatures

 

[U.Toadifact]

A black mass will radiate more heat to the environment than a lighter colour so the black (or darker) item will tend to be cooler.

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[pandjb]

They aren't colder. If you have two items of different material in the same space over time they will be at the same temperature. They may feel colder to the touch but that's only due to thermal conductivity.

This is correct ( Physics teacher for 36 yrs!). The one which feels cooler only does so because it conducts heat away from your hand at a greater rate due to its higher thermal conductivity. Polystyrene 'feels' warm to the touch because it has a very low thermal conductivity, even though it is at the same temperature as its surroundings.

Two materials in same environment can have different temperatures

Yes but not if they are in thermal equilibrium (ie if they have been in the same space for a period of time)

A black mass will radiate more heat to the environment than a lighter colour so the black (or darker) item will tend to be cooler.

A black body radiator in thermal equilibrium with its surroundings will absorb and emit radiation at the same rate, so will stay at the same temperature as its surroundings

 

[autorouter]

Imagine that the limiting factor is the rate of heat flow from the warm/cold air to the wall surface. A better insulated section of wall will maintain a higher temperature difference than a badly insulated section, for the same heat flow rate (that's what 'better insulated' means).

The badly insulating section will have a lower temperature on the warm side, and a higher temperature on the cold side, compared to the well-insulated section.

So the warm side will feel colder, first because it is a better heat conductor, but also because its temperature is lower too. The two effects reinforce each other, so the effect is more noticeable.

On the outside, the badly insulated section will feel colder because it is a better heat conductor, but will feel warmer because it's at a higher temperature. The well insulated section will feel the opposite. The upshot is, the different feelings will cancel to some extent, so they will feel less different than the sections on the warm side.

 

[Tombola]

due to thermal conductivity

I think you may have answered your own question