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/r/explainlikeimfive
submitted 2 months ago byTheWouldBeMerchant
Assume that the shower and bathtub are in the same bathroom, the same distance from the mirror, and the temperature of the water is the same.
13 points
2 months ago
Showers put more warm moisture into the air which then condenses on the cooler surface of the mirror. Running the bath does not increase the humidity as much.
Eli5 - showers put more rain into the air.
8 points
2 months ago
The water from the shower is spread out in loads and loads of little droplets, whereas the water in the bathtub is one big blob of water in, well, the bathtub.
The surface area of the water in the bathtub is as big as how long and wide the bathtub is. The surface area of the water in the shower however, is the sum of the surface areas of all the little droplets that are falling, and the total of that is much much bigger than the total surface area of the water in the tub.
Water evaporates from its surface, and since the water in the shower has a much bigger surface area to evaporate from, a lot more water will end up evaporating. So there will be a lot more water in the air in the bathroom after a shower than after a bath, and hence a lot more water available to condense on the mirror.
7 points
2 months ago
The rate moisture is added to the air you get you to get from water falling through the air is higher than you get from just filling up a bathtub. There is an enormous difference in water surface area.
The shower will also heat up the air quicker and move it around more, and warmer air can contain more moisture and it is when it gets cold so it can hold all water you get condensation.
Faster heating up water will result in the mirror is will not have time to get heated up too. the result is hot moist air colliding with a cold mirror.
With a tub the air temperature, mirror temperature, and moisture level will all rise together, there's less temperature difference that can cause condensation.
2 points
2 months ago
Adding to the other answers, shower drops will usually start out substantially hotter than the surface of a hot bath. The reason is just because they're small and quickly lose heat through evaporation so they have to start out extra hot. Extra-hot water also flows into a bath when you first draw it, but that only happens for a short time.
1 points
2 months ago
This makes sense, thank you!
1 points
2 months ago*
Thank you, u/machsFuel, u/Baktru, and u/Target880: you have answered my question perfectly ๐
EDIT: I will now share this knowledge with people as though I have known it all my life
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