How to Choose weather globes?

Proposed meteorological instrument

The storm glass or chemical weather glass was an instrument claimed to help predict weather. It consists of a special liquid placed inside a sealed transparent glass. The state of crystallization within the liquid was believed to be related to the weather. The inventor is unknown but the device became popular in the 1860s after being promoted by Royal Navy Admiral Robert FitzRoy who claimed that

if fixed, undisturbed, in free air, not exposed to radiation, fire, or sun, but in the ordinary light of a well-ventilated room or outer air, the chemical mixture in a so-called storm-glass varies in character with the direction of the wind, not its force, specially (though it may so vary in appearance only) from another cause, electrical tension.

The compositions of the liquid in a storm glass varies but usually contains "camphor, nitrate of potassium and sal-ammoniac, dissolved by alcohol, with water and some air." These devices are now known to have little value in weather prediction but continue to be a curiosity.[1]

Description

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The liquid within the glass is a mixture of several ingredients, most commonly distilled water, ethanol, potassium nitrate, ammonium chloride, and camphor. This specific mixture was promoted by Admiral Robert FitzRoy although similar devices existed even two decades earlier with variants in Italy, France and Germany.[2][3][4][5]

FitzRoy carefully documented his claims on how the storm glass would predict the weather:[2][failed verification]

• A catalogue of storm glasses c. 1863If the liquid in the glass is clear, the weather will be bright and clear.
• If the liquid is cloudy, the weather will be cloudy as well, perhaps with precipitation.
• If there are small dots in the liquid, humid or foggy weather can be expected.
• A cloudy glass with small stars indicates thunderstorms.
• If the liquid contains small stars on sunny winter days, then snow is coming.
• If there are large flakes throughout the liquid, it will be overcast in temperate seasons or snowy in the winter.
• If there are crystals at the bottom, this indicates frost.
• If there are threads near the top, it will be windy.

A version of the device was available in the 18th century in France and the inventor is unknown.[5] In 1859, violent storms struck the British Isles. In response, the British Crown distributed storm glasses, then known as "FitzRoy's storm barometers," to many small fishing communities around the British Isles for consultation by ships in port before setting sail.

Accuracy

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In 1863 Charles Tomlinson published an analysis in The Philosophical Magazine concluding that while attractive, "I think it may fairly be concluded from these experiments and observations that the storm-glass acts as a crude kind of thermoscope, inferior, for most of the purposes of observation, to the thermometer."[1] In 2008 an article in the Journal of Crystal Growth similarly concluded that temperature change is the sole cause of crystal growth in storm glasses.[6]

See also

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• Tempest Prognosticator – an alternative to the storm glass that the British government investigated

References

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Weather Forecast Storm Glass consists of a special liquid placed inside a sealed transparent glass. Even now so little complete use is made of the instrument. Many barometers and thermometers often show what may be expected a day or even days in advance. Rather than the weather of the present or next few hours.

Wind or its direction affects the storm glass much more than rain or snow. Allowance should always be made for days as well as for hours to come.

Weather forecast glass is meant for the indication of weather changes or its duration. Those of a superior kind of weather instruments are needed for tests and for science.

Weather glass is not influenced by pressure like barometers. Nor entirely by temperature like thermometers. Electrical tension that is being caused in the air during weather changes. Believed to be another element that affects the weather predicting storm glass

Temperature affects the mixture much but not entirely. Examples of winter with summer changes of temperature can prove to you. It is advisable to consider this for any weather forecaster. That is trying to foretell the coming weather by a change of crystals inside a stormglass.

As helpful as these general formations are in most cases, they can be sometimes inaccurate. Therefore, conclusions may be very quickly formed tending to discourage the inexperienced in the weather forecast.

It should always be remembered that the state of air foretells coming weather rather than indicates weather that is present. An invaluable fact too often overlooked - that the longer the time between the signs and the change foretold by weatherglass. The longer such altered weather will last and on the contrary. The less the time the shorter will be the continuance of such weather. Crystal patterns inside the bottle can easily deceive the person. Who from the signs alone expects to see immediate weather changes