Julius von Hann

Julius Ferdinand von Hann (23 March 1839 in Wartberg ob der Aist near Linz – 1 October 1921 in Vienna) was an Austrian meteorologist. He is seen as a father of modern meteorology.

Julius Ferdinand von Hann
Born	(1839-03-23)March 23, 1839 Wartberg ob der Aist near Linz
Died	October 1, 1921(1921-10-01) (aged 82) Vienna
Nationality	Austrian
Occupation	Meteorologist

Biography

He was educated at the gymnasium of Kremsmünster and then studied mathematics, chemistry and physics at the University of Vienna, then geology and paleontology under Eduard Suess and physical geography under Friedrich Simony. 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, but returned to Vienna to fill the chair of professor of cosmic physics in 1900, where he remained until 1910. In 1912, he was made a foreign knight of the Prussian Ordre Pour le Mérite.

Hann window

Hann invented a weighted moving average technique for combining meteorological data from neighboring regions, using the weights [1/4, 1/2, 1/4], known as Hann smoothing.[1][2]

In signal processing, the Hann window is a window function, called the Hann function, derived from this technique by R. B. Blackman and John Tukey in 1959.[3] Here, the use of the Hann window is called "hanning", e.g., "hanning" a signal is to apply the Hann window to it.[4]

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

1. Hann, Julius von (1903). Handbook of Climatology. Macmillan. p. 199. The figures under b are determined by taking into account the parallels 5° away on either side. Thus, for example, for latitude 60° we have ½[60+(65+55)÷2].
2. Kahlig, Peter (1993), "Some aspects of Julius von Hann's contribution to modern climatology", in McBean, G.A.; Hantel, M. (eds.), Interactions Between Global Climate Subsystems: The Legacy of Hann, Geophysical Monograph Series, 75, American Geophysical Union, pp. 1–7, doi:10.1029/gm075p0001, ISBN 9780875904665, retrieved 2019-07-01, Hann appears to be the inventor of a certain data smoothing procedure, now called "hanning" ... or "Hann smoothing" ... Essentially, it is a three-term moving average (running mean) with unequal weights (1/4, 1/2, 1/4).
3. Blackman, R. B.; Tukey, J. W. (1958). "The measurement of power spectra from the point of view of communications engineering — Part I". The Bell System Technical Journal. 37 (1): 273. doi:10.1002/j.1538-7305.1958.tb03874.x. ISSN 0005-8580.
4. Harris, Fredric J. (Jan 1978). "On the use of Windows for Harmonic Analysis with the Discrete Fourier Transform" (PDF). Proceedings of the IEEE. 66 (1): 51–83. Bibcode:1978IEEEP..66...51H. CiteSeerX 10.1.1.649.9880. doi:10.1109/PROC.1978.10837. The correct name of this window is “Hann.” The term “Hanning” is used in this report to reflect conventional usage. The derived term “Hann’d” is also widely used.

References

•  Chisholm, Hugh, ed. (1922). "Hann, Julius von" . Encyclopædia Britannica (12th ed.). London & New York.
• "Hann, Julius Ferdinand von." Complete Dictionary of Scientific Biography. 2008. Encyclopedia.com. (June 26, 2014).