Passage: In 1924 Wegener was appointed to a professorship in meteorology and geophysics in Graz, which finally provided him with a secure position for himself and his family. He concentrated on physics and the optics of the atmosphere as well as the study of tornadoes. He had studies tornadoes for several years by this point, publishing the first thorough European tornado climatology in 1917. He also posited tornado vortex structures and formative processes. Scientific assessment of his second Greenland expedition (ice measurements, atmospheric optics, etc.) continued to the end of the 1920s.

Question: What did Wegener focus optics on?
atmosphere