I just put like half a cup of water in a mason jar and put that in the microwave and accidentally left it in there for to long and it got boiling hot, then when I took it out and let it cool of course the glass cooled much quicker near the top away from the boiling liquid, and there was some very thick nice steam, one other variable is it's pretty cold in my house today. Anyways looking at the steam in the jar I was reminded of a cloud chamber I once saw which could detect cosmic rays, but looking at the steam closely for several minutes I didn't see any. Come to think of it I've NEVER seen cosmic rays in clouds that I've uhm... "created" so what is the difference between what I can make with a jar and a microwave, and what scientists make for cr detection? And as a bonus question how could the microwave/ water jar set up possibly be improved?


1 Answer 1


Cloud chambers require a supersaturated environment such as one created by cooling a sealed chamber filled with alcohol vapor. The high velocity cosmic ray particles ionize the gas molecules they come in contact with. This causes the gas particles to condense at those places leaving a visible trail. Steam in a microwave would not usually be supersaturated.

A simple cloud chamber can be created by using a sealed container (ie 10 gallon fish tank, large glass/plastic jar, etc) with a cloth/sponge saturated with alcohol at the top and dry ice under the container. The alcohol will evaporate saturating the air near the top, as it is cooled below that it becomes supersaturated.


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    $\begingroup$ Ah so the streak is alcohol steam that wasn't there before, and precipitated easily due to super saturation. Is there such a thing as super saturating water vapor? $\endgroup$
    – user273872
    Commented Nov 10, 2017 at 22:42
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    $\begingroup$ Yes, it is possible to supersaturate with water, however it would seem to be more difficult. $\endgroup$
    – Stel
    Commented Nov 10, 2017 at 22:47
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    $\begingroup$ @Stel much more difficult. Probably not possible in a mason jar. I also assume the mason jar was open, because otherwise the metal lid would have messed up the microwave. $\endgroup$
    – user166904
    Commented Nov 11, 2017 at 17:25

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