Discovery of the Stratosphere

Léon Philippe Teisserenc de Bort was a French experimental meteorologist whose research with high altitude balloons led to the discovery of the stratosphere. He lived from 1855 until 1913. He conducted his key work from 1898 until 1902. In 1902 he published a famous paper suggesting that there was a two layer atmosphere. Conventional weather systems, and convective heat transfer, take place in the lower layer, or troposphere. The upper layer, or stratosphere, is dominated by heat transfer by radiation  

From 1880 until 1896 Léon Philippe Teisserenc de Bort worked for the French ‘ Bureau Central Météorologique where he took an interest in the variation in pressure with altitude and rose to the rank of chief meteorologist. In 1896 he left the Bureau and established his own private meteorological observatory in Trappes near Versailles.

At his private observatory Léon Philippe Teisserenc de Bort took an interest in clouds and the physics of the upper atmosphere. He conducted studies using his own highly instrumented hydrogen balloons. His balloon technology anticipated the development of high altitude balloons that would later discovery cosmic rays and travel to the edge of the Earth’s atmosphere.

In 1898, when Léon Philippe Teisserenc de Bort wrote up his research in the prestigious ”Comptes Rendus”, he reached a puzzling conclusion. He found that the atmosphere became cooler with altitude, but only up to a certain height which he called the troposphere. Above the troposphere his research implied that temperature did not increase with height. From the troposphere to the highest altitudes that he could reach the temperature of the atmosphere did not change with height. Although his research implied that there two layers to the atmosphere Léon Philippe Teisserenc de Bort conducted over 200 further balloon flights to confirm his hypothesis. Many of the flights took place at night to prevent his instruments being warmed by solar radiation. The findings were complicated because the height of the troposphere can vary due to meteorological conditions. Léon Philippe Teisserenc de Bort found that the troposphere extended variously from 8 kilometres to 17 kilometres above the Earth’s surface.

In 1908 Léon Philippe Teisserenc de Bort finally published a paper confirming the existence of a two layer atmosphere. He released that there was little mechanism to exchange air between the two atmospheres. In 1909 E. Gold  explained that the troposphere (or weather system) was dominated by convection currents causing the expansion and cooling of rising air whereas the stratosphere lacked convection currents and was dominated by horizontally moving air flows. Scientists later realised that the absence of mixing between the troposphere and stratosphere meant that particles injected into the stratosphere, from volcanic, nuclear explosions and aircraft exhaust origins, could stay in the upper atmosphere for years.

The discovery of the stratosphere was an important scientific milestone. It led indirectly to the development of commercial aviation. Aviation uses the stratosphere to avoid the dangers of weather systems and turbulence to save fuel by flying in the less dense air. The work of  Léon Philippe Teisserenc de Bort also led, fifty years later, to the discovery of the jet streams in the lower stratosphere. These winds can greatly help, or delay, aviation flights. Although not a part of the troposphere these winds help to steer weather systems across the Atlantic and into western Europe.