He worked in the fields of spectroscopy, atmospheric physics and meteorology. In the field of spectroscopy he found the shift of spectral lines under pressure. In atmospheric physics he found a very good model for the stratosphere in 1909. He wrote numerous books, including a textbook titled "Physics of the Air", first published in 1920 and considered a standard work of the time, though it was last published in 1940. He also held some teaching positions at universities. He concluded that the 1815 eruption of Mount Tambora was responsible for the subsequent cooling known as the Year Without a Summer.