Storm glass

from Wikipedia, the free encyclopedia
Storm glass

A storm glass , also FitzRoy storm glass (after Admiral Robert FitzRoy ) or camphor glass , is a glass tube filled with water , ethanol , camphor , potassium nitrate and ammonium chloride in which crystals in different shapes occasionally grow and then dissolve again. It is claimed that these changes herald storms or bad weather fronts, but a study by chemists at the University of Duisburg-Essen could not confirm such a suitability for weather forecasting.

history

The name of the FitzRoy storm glass probably goes back to the Admiral Robert FitzRoy (1805-1865). FitzRoy was entrusted with setting up a meteorological monitoring network. To do this, he had developed a simple and cheap but accurate mercury barometer (a real pressure gauge) that was to be used throughout England. This barometer was further developed after his death, provided with a thermometer and also with the storm glass named after him. Storm glasses of this type have been sold on London Bridge in England since the 17th century . A certain Barth in Nuremberg is said to have made this weather glass before. FitzRoy noted in his meteorology book the usefulness of the storm glass for predicting weather changes, although it was rejected by scientists because there was no scientific explanation for the observable changes in the glass related to the weather (apart from changes in ambient temperature).

Structure and mode of operation

The glass consists of a sealed glass tube with a saturated camphor - alcohol - solution . Hans Baumer, laboratory manager at Bruckmann Verlag , who researched so-called sferics and later also the storm glass around 1980 , mentions an aqueous solution of potassium nitrate and ammonium chloride mixed with a camphor solution in 90% alcohol. The chemists at the University of Duisburg-Essen analyzed the contents of a storm glass from ES Sørensen, Malov, Denmark. It contained per kg: 243 g water, 243 g ethanol , 363 g camphor, 50 g potassium nitrate and 100 g ammonium chloride.

On the basis of observations it was assumed that crystals grow in the solution depending on the change in weather. During the second voyage of the HMS Beagle , FitzRoy and Charles Darwin worked out the following interpretation of the crystal growth:

  • When the liquid in the glass is clear, the weather will be sunny and clear.
  • If the liquid is flaky, it will be cloudy. Precipitation is possible.
  • When tiny flakes float in the liquid, you can expect damp, foggy weather.
  • A cloudy glass with small stars indicates a thunderstorm.
  • If there are small stars in the liquid on a beautiful winter day, it will snow.
  • If there are large flakes all over the liquid, it will become covered or snow will fall in winter, depending on the season.
  • When there are many crystals on the ground, there is frost.
  • When crystals form on the surface, it gets stormy.

The storm glass should allow a forecast over a period of about 24 to 36 hours.

One theory about the phenomenon of crystal growth, which is often quoted, is based on the fact that a storm front is usually heralded by falling air pressure. The air pressure acts on the inside of the glass, particularly in the case of variants of the storm glass that are not sealed gas-tight. At lower pressure, the amount of foreign matter that can be dissolved in a liquid without it becoming oversaturated should be lower. The reduced air pressure is supposed to lead to a temporary supersaturation of the solution and as a result crystals temporarily formed. Critics of this theory argue that the solubility of solids hardly depends on the pressure, and that storm glasses whose glass is sealed gas-tight also seem to work. In this case, the influence of the air pressure is several orders of magnitude smaller and therefore probably no longer relevant.

Hans Baumer wants to exclude temperature and pressure as essential influencing factors through his own experiments and came to the result that the size of the crystals in his glass is essentially linked to the occurrence of electromagnetic longitudinal waves, so-called sferics. These sferics occur mainly in low pressure areas in areas where air is lifted or rises due to atmospheric instability. The storm glass therefore shows sferics and thus the approaching low pressure area, i.e. bad weather. FitzRoy is said to have already suspected that air electricity - which can be interpreted in the broadest sense as electromagnetic waves - is the cause of crystal growth.

The chemists at the University of Duisburg-Essen observed the crystals in a storm glass made according to their analyzes (see above) and located in a building for about 13 months and examined the phenomena for correlations with weather factors on the same day and the seven following days. As weather factors, they recorded air pressure , outside temperature, amount of precipitation , wind direction and speed and UV index , and they also recorded the temperature of the storm glass environment. No correlation was found with any of the weather variables with the following exceptions: If crystals floating downwards formed, which, however, rarely happened, there was a certain probability that a high air pressure would arise in the following three to five days, and the appearance of the crystals changed back to another condition, the air pressure was back to normal in the next few days. Bad weather or storms could not be predicted from the appearance of the crystals; none of the appearances was associated with particularly low air pressure. The ambient temperature of the storm glass, on the other hand, had a significant influence on the crystal image: More crystals at a lower temperature and vice versa. Experiments with solutions in which potassium nitrate, ammonium chloride, water or ethanol were omitted showed that all of these components are necessary for the typical formation and change in the crystal phenomena.

  • Detail of crystals in storm glass

  • Crystals in the storm glass

  • Crystals in the storm glass

  • Crystals in the storm glass

According to the Journal of Crystal growth , changes in crystal structure are solely due to changes in ambient temperature.

literature

  • Bert Bolle: Old barometers. translated by Christian Zinsser, Callwey, Munich 1980, ISBN 3-7667-0534-2 .

See also

Web links

  • Andreas bag shows its weather pages Webcam -Pictures by a storm glass and here the changes for months in lapse .
  • On the website of the Bild der Wissenschaft Shop , the conditions under different weather conditions are shown as a sketch and a time-lapse video shows the growth of the crystals.
  • Image of FitzRoy's storm glass mercury barometer and the history of the barometer on the English page of antique dealer Charles Edwin.
  • English-language building instructions for the storm glass and a time-lapse video of the crystal growth can be found at instructables.com .

Individual evidence

  1. ^ A b Paulina Kaempfe, Karl Molt, Matthias Epple : Admiral Fitzroys legendary storm glass. In: Chemistry in Our Time. Vol. 46, February 2012, pp. 26–31, doi: 10.1002 / ciuz.201100563 .
  2. ↑ Bert Bolle: Old Barometer. translated by Christian Zinsser, Callwey, Munich 1980, ISBN 3-7667-0534-2 .
  3. ↑ Hans Baumer: Sferics, the discovery of weather radiation. Rowohlt, Reinbek bei Hamburg 1987, ISBN 3-498-00487-5 , p. 163
  4. ↑ Hans Baumer: Sferics, the discovery of weather radiation. Rowohlt, Reinbek bei Hamburg 1987, ISBN 3-498-00487-5 , pp. 162-175
  5. ↑ Yasuko Tanaka, Koichi Hagano, Tomoyasu Kuno, Kazushige Nagashima: Pattern formation of crystals in storm glass . In: Journal of Crystal Growth . tape 310 , no. 10 . Kawasaki May 1, 2008, p. 2668–2672 , doi : 10.1016 / j.jcrysgro.2008.01.037 , bibcode : 2008JCrGr.310.2668T .