Léon Philippe Teisserenc de Bort (November 5, 1855 in Paris, France – January 2, 1913 in Cannes, France) was a French meteorologist who became famous for his discovery of the stratosphere.

Instrumented balloons pioneer

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. Between 1892 and 1896, Teisserenc de Bort was the chief of the Administrative Center of National Meteorology (a department of the French government) in Paris. After his resignation from this post he established a private meteorological observatory in Trappes near Versailles. There he conducted experiments with high-flying instrumented balloons and was one of the first people to use such devices.

Bort noticed that while the air temperature decreased steadily up to approximately 11 kilometers of height, it remained constant above that altitude (up to the highest points he could reach). In other words, he discovered an indication of a temperature inversion or at least of a zero lapse rate above this altitude. For many years he was uncertain whether he discovered a true physical phenomenon or whether his measurements suffered from a systematic bias (indeed, the first measurements did have a positive temperature bias as the instruments were liable to radiative heating by solar radiation). That is why Teisserenc de Bort carried out 200+ more balloon experiments (with a substantial part of them being held during the night to eliminate radiative heating) until 1902, when he suggested that the atmosphere was divided into two layers.

Troposphere and stratosphere

During the years that followed, he named the two layers of the atmosphere known at that time the "troposphere" and the "stratosphere". This naming convention has since been maintained, with (higher-altitude) layers that were subsequently discovered being given names of this sort. After Teisserenc de Bort's death in 1913, the heirs donated the observatory to the state so that the research tasks could be continued.

Named after him

• Teisserenc crater on the Moon.
• Teisserenc de Bort crater on Mars.

External links

• History of the Teisserenc de Bort observatory