I was recently reading about Admiral Robert FitzRoy's storm glass and how it was used to predict the weather conditions based on the formation of camphor crystals in a sealed glass tube containing distilled water, ethanol, potassium nitrate, ammonium chloride, and camphor.

I started searching for the possible explanations of its working. The first one I encountered stated that it only worked on the changes in atmospheric temperature and was nothing but a thermometer. But there were other articles (like How to Make Fitzroy's Storm Glass) stating that there are also some electromagnetic and quantum (quantum tunneling) explanations for the appearance of crystals and how the atmospheric pressure affects the crystal formation even though the glass tube is SEALED.

I searched for these explanations but couldn't find them. Does anyone have any idea how one can apply the concepts of electromagnetism and quantum tunneling to explain the formation of crystals with the change in weather and how atmospheric pressure might influence the contents of a sealed glass tube.

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    $\begingroup$ I highly doubt that electromagnetism or quantum tunneling have anything to do with the observed behavior. Simple temperature variations would seem to be the most likely cause. The behavior would likely depend on how fast the temperature changes as well as the high and low temperatures. $\endgroup$
    – MaxW
    Apr 9, 2016 at 6:04
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    $\begingroup$ Well, since Wikipedia starts with "A storm glass is a type of weather forecasting device, composed of a sealed glass container filled with liquid. The appearance of the liquid purportedly predicts the weather, but most modern experiments have failed to confirm this.", I would chime in and declare skepticism of the purported function until someone presents hard data to the opposite. $\endgroup$
    – CuriousOne
    Apr 9, 2016 at 6:30
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    $\begingroup$ Sounds like a sophisticated way of reading tea leaves and equally accurate! $\endgroup$
    – Gert
    Apr 9, 2016 at 13:44
  • $\begingroup$ There is an interesting but short paper from Taiwan. It also has a good reference list, but those items seems not available for public reading. edu.utsunomiya-u.ac.jp/chem/v15n2/110Jong/Jong3112t.pdf All in all they argue for temperature change between 14C and 23C and speed of that change influencing the crystal by moving solubility around the critical point $\endgroup$
    – Arioch
    Apr 4 at 23:35

1 Answer 1


Recently, as part of the debate on climate change, it has been proposed that cosmic rays have an influence on the nucleation of water particles that initiate the formation of clouds. It is possible that a similar effect aids initiation of camphor crystals. As clouds mean rain then perhaps this explains the clouding of the solution. Clearly temperature will also have some effect as the combination of clouding and lower temperature would result in more crystal formation indicating snow. One wonders if siting the storm glass in full sun or in shade would make a difference on its performance as one would expect no crystals if the glass is in full sun. Another issue is that the weather tomorrow is more likely to be the same as the weather today than it is to change so the predictive capability of the glass must be questionable.

  • $\begingroup$ This hypothesis should be extremely easy to test, as cosmic ray intensity does vary with time, mainly correlated to the Sun's cycles, if I understand right. Do you have any references for measurements correlations between CR intensity and the activity in the admiral's glass? $\endgroup$ Feb 15, 2018 at 7:13

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