Editing Weather forecasting (section)

===Numerical prediction===
{{Main|History of numerical weather prediction}}
[[File:Improved-weather-forecasting 7463.png|thumb|The difference between the forecast and the actual weather outcome for forecasts 3, 5, 7, and 10 days in advance.]]
It was not until the 20th century that advances in the understanding of atmospheric physics led to the foundation of modern [[numerical weather prediction]]. In 1922, English scientist [[Lewis Fry Richardson]] published "Weather Prediction By Numerical Process",<ref>Richardson, Lewis Fry, ''Weather Prediction by Numerical Process'' (Cambridge, England: Cambridge University Press, 1922). Available on-line at: [https://archive.org/stream/weatherpredictio00richrich#page/n7/mode/2up Internet Archive.org].</ref> after finding notes and derivations he worked on as an ambulance driver in World War I. He described therein how small terms in the prognostic fluid dynamics equations governing atmospheric flow could be neglected, and a finite differencing scheme in time and space could be devised, to allow numerical prediction solutions to be found.

Richardson envisioned a large auditorium of thousands of people performing the calculations and passing them to others. However, the sheer number of calculations required was too large to be completed without the use of computers, and the size of the grid and time steps led to unrealistic results in deepening systems. It was later found, through numerical analysis, that this was due to [[numerical instability]].<ref>[[Peter Lynch (meteorologist)|Lynch, Peter]] (2006). The Emergence of Numerical Weather Prediction. Cambridge University Press</ref> The first computerised weather forecast was performed by a team composed of American meteorologists [[Jule Charney]], [[Philip Duncan Thompson]], [[Larry Gates]], and Norwegian meteorologist [[Ragnar Fjørtoft]], applied mathematician [[John von Neumann]], and [[ENIAC]] programmer [[Klara Dan von Neumann]].<ref>{{cite journal|doi=10.3402/tellusa.v2i4.8607|title=Numerical Integration of the Barotropic Vorticity Equation|journal=Tellus|volume=2|issue=4|pages=237–254|year=1950|last1=Charney|first1=J. G.|last2=Fjörtoft|first2=R.|last3=von Neumann|first3=J.|bibcode=1950Tell....2..237C|doi-access=free}}</ref><ref>{{cite magazine |last1=Witman |first1=Sarah |title=Meet the Computer Scientist You Should Thank For Your Smartphone's Weather App |url=http://www.smithsonianmag.com/science-nature/meet-computer-scientist-you-should-thank-your-phone-weather-app-180963716/ |magazine=Smithsonian |date=June 16, 2017 |access-date=July 22, 2017 |archive-date=April 21, 2019 |archive-url=https://web.archive.org/web/20190421001535/https://www.smithsonianmag.com/science-nature/meet-computer-scientist-you-should-thank-your-phone-weather-app-180963716/ |url-status=live }}</ref><ref>{{cite book|last=Edwards|first=Paul N.|title=A Vast Machine: Computer Models, Climate Data, and the Politics of Global Warming|year=2010|publisher=The MIT Press|isbn=978-0262013925|url=http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=12080|url-status=dead|archive-url=https://web.archive.org/web/20120127215929/http://mitpress.mit.edu/catalog/item/default.asp?ttype=2&tid=12080|archive-date=January 27, 2012}}</ref> Practical use of numerical weather prediction began in 1955,<ref>Paul N. Edwards. [http://www.aip.org/history/sloan/gcm/ "Atmospheric General Circulation Modeling"]. {{webarchive|url=https://web.archive.org/web/20080325084036/http://www.aip.org/history/sloan/gcm/ |date=March 25, 2008 }} Retrieved February 16, 2007.</ref> spurred by the development of programmable electronic computers.