Julius Ferdinand von Hann (23 March 1839 in

Wartberg ob der Aist Wartberg ob der Aist is a municipality in the district of Freistadt in the Austrian state of Upper Austria. Population Personalities Wartberg is the birthplace of Austrian Roman Catholic The Catholic Church (), also known as the Rom ...

near Linz – 1 October 1921 in

Vienna Vienna ( ; ; ) is the capital city, capital, List of largest cities in Austria, most populous city, and one of Federal states of Austria, nine federal states of Austria. It is Austria's primate city, with just over two million inhabitants. ...

) was an

Austria Austria, formally the Republic of Austria, is a landlocked country in Central Europe, lying in the Eastern Alps. It is a federation of nine Federal states of Austria, states, of which the capital Vienna is the List of largest cities in Aust ...

meteorologist A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmosphere of Earth, atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists ...

. He is seen as a father of modern meteorology.

Biography

He was educated at the gymnasium of

Kremsmünster Kremsmünster is a town in Kirchdorf an der Krems District, in the Austrian state of Upper Austria. Settled in 777, it is home to the Kremsmünster Abbey. The Abbey was founded 777 by Duke Tassilo III of Bavaria and is one of the oldest abbeys ...

and then studied

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

chemistry Chemistry is the scientific study of the properties and behavior of matter. It is a physical science within the natural sciences that studies the chemical elements that make up matter and chemical compound, compounds made of atoms, molecules a ...

and

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

at the

University of Vienna The University of Vienna (, ) is a public university, public research university in Vienna, Austria. Founded by Rudolf IV, Duke of Austria, Duke Rudolph IV in 1365, it is the oldest university in the German-speaking world and among the largest ...

, then geology and paleontology under

Eduard Suess Eduard Suess (; 20 August 1831 – 26 April 1914) was an Austrian geologist and an expert on the geography of the Alps. He is responsible for hypothesising two major former geographical features, the supercontinent Gondwana (proposed in 1861) and ...

and physical geography under

Friedrich Simony Friedrich Simony (30 November 1813, Hrochův Týnec, Hrochowteinitz – 20 July 1896, Sankt Gallen, Styria, Sankt Gallen) was an Austrian geographer and Alpinist, Alpine researcher. Initially trained as a pharmacist, from 1836 he studied natur ...

. From 1865 to 1868, he was master at the ''Oberrealschule'' at Linz, and in 1865 was invited by Karl Jelinek to become the first editor of the '' Zeitschrift für Meteorologie''. In 1877, he succeeded Jelinek as the director of the Meteorologische Zentralanstalt (Central Institute for Meteorology and Earth Magnetism) and was appointed professor of meteorology at the University of Vienna. In 1897, he retired as director and became professor of meteorology at the

University of Graz The University of Graz (, formerly: ''Karl-Franzens-Universität Graz'') is a public university, public research university located in Graz, Austria. It is the largest and oldest university in Styria, as well as the second-largest and second-old ...

, but returned to Vienna to fill the chair of professor of cosmic physics in 1900, where he remained until 1910. He became an international honorary member of the

American Academy of Arts and Sciences The American Academy of Arts and Sciences (The Academy) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, and other ...

in 1902. In 1912, he was made a foreign knight of the

Prussia Prussia (; ; Old Prussian: ''Prūsija'') was a Germans, German state centred on the North European Plain that originated from the 1525 secularization of the Prussia (region), Prussian part of the State of the Teutonic Order. For centuries, ...

n ''Ordre Pour le Mérite''.

Hann window

Hann invented a

weighted moving average In statistics, a moving average (rolling average or running average or moving mean or rolling mean) is a calculation to analyze data points by creating a series of averages of different selections of the full data set. Variations include: simple ...

technique for combining meteorological data from neighboring regions, using the weights /4, 1/2, 1/4 known as ''Hann smoothing''. In

signal processing Signal processing is an electrical engineering subfield that focuses on analyzing, modifying and synthesizing ''signals'', such as audio signal processing, sound, image processing, images, Scalar potential, potential fields, Seismic tomograph ...

, the Hann window is a

window function In signal processing and statistics, a window function (also known as an apodization function or tapering function) is a mathematical function that is zero-valued outside of some chosen interval. Typically, window functions are symmetric around ...

, called the

Hann function The Hann function is named after the Austrian meteorologist Julius von Hann. It is a window function used to perform Hann smoothing or hanning. The function, with length L and amplitude 1/L, is given by: : w_0(x) \triangleq \left\. For ...

, derived from this technique by R. B. Blackman and

John Tukey John Wilder Tukey (; June 16, 1915 – July 26, 2000) was an American mathematician and statistician, best known for the development of the fast Fourier Transform (FFT) algorithm and box plot. The Tukey range test, the Tukey lambda distributi ...

in 1959. Here, the use of the Hann window is called "hanning", e.g., "hanning" a signal is to apply the Hann window to it.

Works

* Die Erde als Ganzes, ihre Atmosphäre und Hydrosphäre, 1872, 5th edition 1896 * Handbuch der Klimatologie, first issued 1883, revised editions until 1911 ** * Atlas der Meteorologie, 1887 * Allgemeine Erdkunde. Ein Leitfaden der astronomischen Geographie, Meteorologie, Geologie und Biologie, 5th edition 1896 * Lehrbuch der Meteorologie, 1901, 3rd edition 1915 He contributed many papers to the ''Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften''.

Notes

References

* * "Hann, Julius Ferdinand von." Complete Dictionary of Scientific Biography. 2008. Encyclopedia.com. (June 26, 2014)

{{DEFAULTSORT:Hann, Julius Von Austrian meteorologists Austrian untitled nobility Recipients of the Buys Ballot Medal (Netherlands) Recipients of the Pour le Mérite (civil class) 1839 births 1921 deaths Academic staff of the University of Vienna Members of the Royal Society of Sciences in Uppsala Scientists from Austria-Hungary Recipients of the Cothenius Medal