Julius von Hann
He was educated at the gymnasium of Kremsmünster and then studied mathematics, chemistry and physics at the University of Vienna. From 1865 to 1868, he was master at the Oberrealschule at Linz, and in 1865 was appointed editor of the Zeitschrift für Meteorologie. In 1877, he became director of the Meteorologische Zentralanstalt (Central Institute for Meteorology) and professor of meteorology at the University of Vienna. In 1897, he 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 
In signal processing, the Hann window is a window function, called the Hann function, named after him by R. B. Blackman and John Tukey in "Particular Pairs of Windows," published in "The Measurement of Power Spectra, From the Point of View of Communications Engineering", New York: Dover, 1959, pp. 98-99.
In the aforementioned article, the use of the Hann window is called "hanning", e.g., "hanning" a signal is to apply the Hann window to it.
- Die Erde als Ganzes, ihre Atmosphäre und Hydrosphäre, 1872
- Handbuch der Klimatologie, 1883
- Atlas der Meteorologie, 1887
- Lehrbuch der Meteorologie, 1901
He contributed many papers to the Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften.