Brynjulf Ottar (1918–1988) was a Norwegian atmospheric chemist who served as the first director of the Norwegian Institute for Air Research. In the 1970s, his pioneering work on the long-range transport of air pollution helped to alert the world to the problem of acid rain; later, he was one of the first scientists to describe the mechanism of global distillation (the "grasshopper effect"), by which pollutants travel from mid-latitude parts of Earth to the Arctic.