Gustav Hellmann
{{short description|German meteorologist (1854–1939)}}
{{Infobox person/Wikidata | fetchwikidata=ALL}}
Gustav Johann Georg Hellmann or Georg Gustav Hellmann (3 July 1854 – 21 February 1939) was a German meteorologist.
Hellmann was born in Löwen (Lewin Brzeski), Prussian Silesia. Since 1907 to 1922, he was the principal of the Preußischen Meteorologischen Institut (Prussian Meteorological Institute) in Berlin. He died in Berlin.
Works
- An editor of the "Meteorologische Zeitschrift" 1892-1907 (with Julius von Hann)
- Repertorium der Deutschen Meteorologie, 1883
- {{cite book | author = Gustav Hellmann | title = Schneekrystalle: Beobachtungen und Studien | publisher = Verlag von Rudolph Mückenberger | year = 1893 | url = https://gdz.sub.uni-goettingen.de/id/PPN560722176}}{{cite book|author=Loraine Daston and Peter Galison|title=Objectivity|publisher = Zone Books| year = 2007 | pages=20,150{{ndash}}151,155,160,325}}
= Work with snowflakes =
In 1892 Hellmann piqued an interest in pictures of snowflakes, after seeing some of Wilson Bentley's photography, he commissioned a microphotographer to take shots of snowflakes to study.{{Cite news|title = The science of snowflakes|url = https://www.theglobeandmail.com/news/national/the-science-of-snowflakes/article7735242/|website = The Globe and Mail|access-date = 2015-11-18}} Upon review of these microphotographs, Hellmann noted a large difference in the snowflake pictures he took, and the ones Wilson Bentley had taken. Hellmann's snowflakes were irregular, there were various types, sizes, shapes, and forms. Bentley's snowflakes however, were perfect, symmetrical, six-sided and reminiscent of stars. Hellmann was perplexed by this, and openly questioned the accuracy of Bentley's work.{{Cite web|title = Under the microscope: snowflakes are not as symmetrical as pictured|url = http://sbstatesman.com/2014/02/18/under-the-microscope-snowflakes-are-not-as-symmetrical-as-pictured/|website = The Statesman|access-date = 2015-11-18}} He accused Bentley of manipulating the snowflake to get these perfect results. Bentley eventually admitted to somewhat doctoring the photographs, by scraping emulsion off the negatives, but he claimed that this did not change the integrity or accuracy of the photograph.{{Cite journal|url = http://docs.lib.noaa.gov/rescue/mwr/028/mwr-028-12-0542.pdf|title = Monthly Weather Review|date = December 1900|journal = Monthly Weather}} This argument persisted for years, Hellmann insisted that altering the snowflake was unethical, as it misrepresented the snowflake in its truest form, Bentley argued the opposite. Although the argument never formally ended with one side winning, it is still Bentley's snowflake the world thinks of when they see snow fall.{{Cite journal|url = http://www.inscc.utah.edu/~tgarrett/Snowflake_Photography_files/Snowflakes%20final%20copy%202013-12-21.pdf|title = No Great Flakes|last = Pilcher|first = Helen|date = 21–28 December 2013|journal = New Scientist|access-date = 2015-11-18}}
= Hellmann number =
In Germany and especially the Netherlands, Hellmann is known for the Hellmann number, a measure for the severity of a winter. This figure is derived by adding up all negative temperatures in the period of 1 November of the previous year up to and including 31 March of the current year.{{Cite news|url=https://www.economist.com/news/europe/21737056-land-champion-speed-skaters-frozen-canals-are-ever-rarer-what-climate-change-means|title=What climate change means for the Netherlands' Olympic skaters|newspaper=The Economist|date=15 February 2018}}
See also
References
{{Reflist}}
External links
- [http://www.infometeo.be/index.php?p=42&letter=H MeteoKust / KiteMeteo - De ultieme kustwebsite met webcams aan zee] at www.infometeo.be (about his meter; Flemish)
- [http://home.planet.nl/~neele050/woordenboek/H.html NEWI Meteo Fijnaart: Weerkundig woordenboek -H-] at home.planet.nl (about his meter; Flemish)
- [http://fa-gem.dmg-ev.de/jubilee2004.html Jubilaeen 2003] at fa-gem.dmg-ev.de (German)
- [http://www.luise-berlin.de/Kalender/Tag/Jul03.htm Chronik: Berlin am 3. Juli, Fakten Jahr für Jahr] at www.luise-berlin.de (German)
- [https://www.knmi.nl/nederland-nu/klimatologie/lijsten/hellmann Hellmann numbers for the Bilt from 1901] at knmi.nl (Dutch)
{{Authority control}}
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Category:German meteorologists
Category:Members of the Prussian Academy of Sciences
Category:People from the Province of Silesia
Category:People from Brzeg County
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