The storm glass is an interesting historical device which claims to be able to predict the weather (for example, clear liquid implies fair weather, murky liquid implies rainy weather and large flaky crystals correspond to cloudy skies and snow in winter).

The liquid in the glass is a mixture of distilled water, ethanol, potassium nitrate, ammonium chloride, and camphor and it has been shown that the crystals which form are camphor. Studies have found that as expected the ability of the device to predict the weather is questionable and that the appearance of crystals is affected only by temperature.

If fair weather is considered ''warm'' (no crystals) and rainy weather is considered ''cold'' (murky water), it seems like decreasing the ambient temperature generally helps crystals to form.

Roughly speaking, what is the reason that one might expect this temperature dependence to occur based on the above ingredients of the storm glass?

The storm glass is an interesting historical device which claims to be able to predict the weather (for example, clear liquid implies fair weather, murky liquid implies rainy weather and large flaky crystals correspond to cloudy skies and snow in winter).

The liquid in the glass is a mixture of distilled water, ethanol, potassium nitrate, ammonium chloride, and camphor and it has been shown that the crystals which form are camphor. To be more specific, it is a camphor-ethanol solution with aqueous ammonium chloride and potassium nitrate solution. Studies have found that as expected the ability of the device to predict the weather is questionable and that the appearance of crystals is affected only by temperature.

If fair weather is considered ''warm'' (no crystals) and rainy weather is considered ''cold'' (murky water), it seems like decreasing the ambient temperature generally helps crystals to form.

Roughly speaking, what is the reason that one might expect this temperature dependence to occur based on the above ingredients of the storm glass?

The storm glass is an interesting historical device which claims to be able to predict the weather (for example, clear liquid implies fair weather, murky liquid implies rainy weather and large flaky crystals correspond to cloudy skies and snow in winter).

The liquid in the glass is a mixture of distilled water, ethanol, potassium nitrate, ammonium chloride, and camphor and it has been shown that the crystals which form are camphor. Studies have found that as expected the ability of the device to predict the weather is questionable and that the appearance of crystals is affected only by temperature.

If fair weather is considered ''warm'' (no crystals) and rainy weather is considered ''cold'' (murky water), it seems like decreasing the ambient temperature generally helps crystals to form.

Roughly speaking, what is the reason that one might expect this to occur based on the above ingredients of the storm glass?

The storm glass is an interesting historical device which claims to be able to predict the weather (for example, clear liquid implies fair weather, murky liquid implies rainy weather and large flaky crystals correspond to cloudy skies and snow in winter).

The liquid in the glass is a mixture of distilled water, ethanol, potassium nitrate, ammonium chloride, and camphor and it has been shown that the crystals which form are camphor. Studies have found that as expected the ability of the device to predict the weather is questionable and that the appearance of crystals is affected only by temperature.

If fair weather is considered ''warm'' (no crystals) and rainy weather is considered ''cold'' (murky water), it seems like decreasing the ambient temperature generally helps crystals to form.

Roughly speaking, what is the reason that one might expect this temperature dependence to occur based on the above ingredients of the storm glass?