Introduction: Create a Storm Glass (Instrument for Weather Prediction)

About: I like turning boring things into awesome things! Usually on video.

Well, it snowed today! +1 for Storm Glass forecast accuracy.

The Storm Glass was first invented in the mid 1700's, and soon made it's way into ships and harbors around Europe to help give warning of approaching bad weather. It gained the most fame through Admiral FitzRoy who used a Storm Glass on the voyage in which he and Darwin traveled to the Galápagos Islands. As such, the instrument is sometimes called a 'FitzRoy Storm Glass'.

Due to the use of vodka rather than pure ethanol and water, the proportions I use to make the Storm Glass in my video breaks somewhat from the traditional ratios, but the recipe is balanced to achieve the same effect as the original. Fortunately, the chemical solution does not require extreme precision to work properly.


  • Vodka, 100 Proof (50% Ethanol) - 300 mL
  • Camphor - 28g (1oz)
  • Potassium Nitrate - 10g
  • Ammonium Chloride - 10g

Some of these chemicals may be difficult to obtain in certain parts of the world, but if Camphor can be found it's possible that Potassium Nitrate or Ammonium Chloride could be substituted for other soluble salts, such as Sodium Chloride (I have not tested this).

To read a Storm Glass for weather prediction, here is a description from the book Pharmaceutical Formulas by Peter MacEwan, published in 1908:


The changes of the solution signify the following:

  • Clear liquid : Bright weather.
  • Crystals at bottom : Thick air, frost in winter.
  • Dim liquid with small stars : Thunderstorms.
  • Large flakes : Heavy air, overcast sky, snow in winter.
  • Threads in upper portion of liquid : Windy weather.
  • Small dots : Damp weather, fog.
  • Rising flakes which remain high : Wind in the upper air regions.
  • Small stars : In winter on bright, sunny days, snow in one or two days.
  • The higher the crystals rise in the glass tube in winter the colder it will be.


The crystals within a Storm Glass will dissolve and solidify all on their own as the temperature changes day to day. If you would like to start fresh with completely clear liquid and watch the crystals form rapidly, the glass can be placed in a bowl of warm water for 10 minutes to dissolve old crystals completely. Remember to loosen the lid before doing so to prevent excess pressure from building inside.

For further reading see:

Thank you for reading! If you cannot view the above video please view this page from a desktop computer. Instructables doesn't always display embedded videos properly on mobile devices. A complete time lapse of a Storm Glass can be viewed on my YouTube channel.