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The storm glass or chemical weather glass is an instrument proposed as a method for predicting 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
The liquid within the glass is a mixture of several ingredients, most commonly 
A version of the device was available in the 18th century in France and the inventor is unknown. In 1859, violent storms struck the British Isles. In response, the
Admiral FitzRoy's remarks on barometers and thermometers
The appearance of crystals in storm glass, when weather changes (video)
Meteorological instrumentation and equipment Glass applications
The storm glass or chemical weather glass is an instrument proposed as a method for predicting 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
The Royal Navy (RN) is the United Kingdom's naval warfare force. Although warships were used by English and Scottish kings from the early medieval period, the first major maritime engagements were fought in the Hundred Years' War against F ...
Admiral Robert FitzRoy
Vice-Admiral Robert FitzRoy (5 July 1805 – 30 April 1865) was an English officer of the Royal Navy and a scientist. He achieved lasting fame as the captain of during Charles Darwin's famous voyage, FitzRoy's second expedition to Tierra de ...
who claimed that 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.
Description
The liquid within the glass is a mixture of several ingredients, most commonly distilled water
Distilled water is water that has been boiled into vapor and condensed back into liquid in a separate container. Impurities in the original water that do not boil below or near the boiling point of water remain in the original container. Thus, di ...
, ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
, potassium nitrate
Potassium nitrate is a chemical compound with the chemical formula . This alkali metal nitrate salt is also known as Indian saltpetre (large deposits of which were historically mined in India). It is an ionic salt of potassium ions K+ and nitrat ...
, ammonium chloride, and camphor
Camphor () is a waxy, colorless solid with a strong aroma. It is classified as a terpenoid and a cyclic ketone. It is found in the wood of the camphor laurel ('' Cinnamomum camphora''), a large evergreen tree found in East Asia; and in the k ...
. This specific mixture was promoted by Admiral Robert FitzRoy
Vice-Admiral Robert FitzRoy (5 July 1805 – 30 April 1865) was an English officer of the Royal Navy and a scientist. He achieved lasting fame as the captain of during Charles Darwin's famous voyage, FitzRoy's second expedition to Tierra de ...
although similar devices existed even two decades earlier with variants in Italy, France and Germany.
FitzRoy carefully documented his claims on how the storm glass would predict the weather:
*If 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
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
.
*If there are small dots in the liquid, humid
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present.
Humidity depen ...
or fog
Fog is a visible aerosol consisting of tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Reprint from Fog can be considered a type of low-lying cloud usually resembling stratus, and is heavily influ ...
gy weather can be expected.
*A cloudy glass with small stars indicates thunderstorm
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are someti ...
s.
*If the liquid contains small stars on sunny winter days, then snow
Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes.
It consists of frozen crystalline water throughout ...
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
Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above-freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase change from water vapor (a gas) ...
.
*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. In 1859, violent storms struck the British Isles. In response, the British Crown
The Crown is the state (polity), state in all its aspects within the jurisprudence of the Commonwealth realms and their subdivisions (such as the Crown Dependencies, British Overseas Territories, overseas territories, Provinces and territorie ...
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
In 1863Charles Tomlinson
Alfred Charles Tomlinson, CBE (8 January 1927 – 22 August 2015) was an English poet, translator, academic, and illustrator.
He was born in Penkhull, and grew up in Basford, Stoke-on-Trent, Staffordshire.
Life
After attending Longton High Sc ...
published an analysis in ''The Philosophical Magazine
The ''Philosophical Magazine'' is one of the oldest scientific journals published in English. It was established by Alexander Tilloch in 1798;John Burnett"Tilloch, Alexander (1759–1825)" Oxford Dictionary of National Biography, Oxford Univer ...
'' 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
A thermoscope is a device that shows changes in temperature. A typical design is a tube in which a liquid rises and falls as the temperature changes. The modern thermometer gradually evolved from it with the addition of a scale in the early 17th c ...
, inferior, for most of the purposes of observation, to the thermometer
A thermometer is a device that temperature measurement, measures temperature or a temperature gradient (the degree of hotness or coldness of an object). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb of a merc ...
."
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.
See also
*Tempest Prognosticator
The tempest prognosticator, also known as the leech barometer, is a 19th-century invention by George Merryweather in which leeches are used in a barometer. The twelve leeches are kept in small bottles inside the device; when they become agitat ...
– an alternative to the storm glass that the British government investigated
References
External links
{{Commonscat, Storm GlassAdmiral FitzRoy's remarks on barometers and thermometers
The appearance of crystals in storm glass, when weather changes (video)
Meteorological instrumentation and equipment Glass applications