How to Make a Storm Glass To Predict the Weather

Weather Forecasting With Chemistry

Crystals form in a storm glass prior to the arrival of a storm.
Crystals form in a storm glass prior to the arrival of a storm. Tim Richardson / EyeEm / Getty Images

You may not feel the approach of impending storms, but the weather causes changes in the atmosphere that affect chemical reactions. You can use your command of chemistry to make a storm glass to help predict the weather.

Storm Glass Materials

How to Make the Storm Glass

  1. Dissolve the potassium nitrate and ammonium chloride in the water.
  1. Dissolve the camphor in the ethanol.
  2. Add the potassium nitrate and ammonium chloride solution to the camphor solution. You may need to warm the solutions to get them to mix.
  3. Either place the mixture in a corked test tube or else seal it within glass. To seal glass, apply heat to the top of the tube until it softens and tilt the tube so the glass edges melt together. If a cork is used, it's a good idea to wrap it with parafilm or coat it with wax to ensure a good seal.

How to Interpret the Storm Glass

  • Clear liquid - weather is predicted to be bright and clear
  • Cloudy liquid - weather may be cloudy as well, perhaps with precipitation
  • Small dots in the liquid - potential humid or foggy weather
  • Cloudy liquid with small stars - thunderstorms or snow, depending on the temperature
  • Large flakes scattered throughout the liquid - overcast skies, possibly with rain or snow
  • Crystals at bottom - frost
  • Threads near the top - wind

    How the Storm Glass Works

    The premise of the functioning of the storm glass is that temperature and pressure affect solubility, sometimes resulting in clear liquid; other times causing precipitants to form. In similar barometers, the liquid level moves up or down a tube in response to atmospheric pressure.

    Sealed glasses are not exposed to the pressure changes that would account for much of the observed behavior. Some people have proposed that surface interactions between the glass wall of the barometer and the liquid contents account for the crystals. Explanations sometimes include effects of electricity or quantum tunneling across the glass.

    History of the Storm Glass

    This type of storm glass was used by Robert FitzRoy, the captain of the HMS Beagle during Charles Darwin's voyage. FitzRoy acted as meteorologist and hydrologist for the journey. FitzRoy stated "storm glasses" had been made in England for at least a century before his 1863 publication of The Weather Book. He had started to study the glasses in 1825. FitzRoy described their properties and noted there was a wide variation in the functioning of the glasses, depending on the formula and method used to create them. The basic formula of the liquid of a good storm glass consisted of camphor, partially dissolved in alcohol, along with water, ethanol, and a bit of air space. FitzRoy emphasized the glass needed to be hermetically sealed, not open to the outside environment.

    Modern storm glasses are widely available online as curiosities.

    The reader may expect variation in their appearance and function, as the formula for making the glass is as much art as science.

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    Your Citation
    Helmenstine, Anne Marie, Ph.D. "How to Make a Storm Glass To Predict the Weather." ThoughtCo, Dec. 4, 2017, Helmenstine, Anne Marie, Ph.D. (2017, December 4). How to Make a Storm Glass To Predict the Weather. Retrieved from Helmenstine, Anne Marie, Ph.D. "How to Make a Storm Glass To Predict the Weather." ThoughtCo. (accessed December 16, 2017).