Storm Glass Instructions

You may not feel the approach of impending storms, but they produce 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

• 2.5 g potassium nitrate
• 2.5 g ammonium chloride
• 33 mL distilled water
• 40 mL ethanol
• 10 g natural camphor

How to Make the Storm Glass

1. Dissolve the potassium nitrate and ammonium chloride in the water.

2. Dissolve the camphor in the ethanol.

3. Add the potassium nitrate and ammonium chloride solution to the camphor solution. You may need to warm the solutions to get them to mix.

4. Either place the mixture in a corked test tube or else seal it within glass.

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.