Léon Teisserenc de Bort, French meteorologist (born 1855)

Léon Philippe Teisserenc de Bort was a French meteorologist and a pioneer in the field of aerology. Together with Richard Assmann (1845-1918), he is credited as co-discoverer of the stratosphere, as both men announced their discovery during the same time period in 1902. Teisserenc de Bort pioneered the use of unmanned instrumented balloons and was the first to identify the region in the atmosphere around 8-17 kilometers of height where the lapse rate reaches zero, known today as the tropopause.

January 2 is the second day of the year in the Gregorian calendar; 363 days remain until the end of the year.