Léon Philippe Teisserenc de Bort (5 November 1855 in

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– 2 January 1913 in

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, France) was a French

meteorologist A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists in research, while t ...

and a pioneer in the field of

aerology Atmospheric science is the study of the Earth's atmosphere and its various inner-working physical processes. Meteorology includes atmospheric chemistry and atmospheric physics with a major focus on weather forecasting. Climatology is the study of ...

. Together with Richard Assmann (1845-1918), he is credited as co-discoverer of the

stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air ...

, as both men announced their discovery during the same time period in 1902. Teisserenc de Bort pioneered the use of unmanned instrumented

balloons A balloon is a flexible bag that can be inflated with a gas, such as helium, hydrogen, nitrous oxide, oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the per ...

and was the first to identify the region in the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

around 8-17 kilometers of height where the

lapse rate The lapse rate is the rate at which an atmospheric variable, normally temperature in Earth's atmosphere, falls with altitude. ''Lapse rate'' arises from the word ''lapse'', in the sense of a gradual fall. In dry air, the adiabatic lapse rate is ...

reaches zero, known today as the

tropopause The tropopause is the atmospheric boundary that demarcates the troposphere from the stratosphere; which are two of the five layers of the atmosphere of Earth. The tropopause is a thermodynamic gradient-stratification layer, that marks the end of ...

Early life and career

He was the son of an engineer. He began his scientific career in 1880, when he entered the meteorological department of the Bureau Central Météorologique (Administrative Centre of National Meteorology, a department of the French government) in

under E. E. N. Mascart. In 1883, 1885 and 1887 he made journeys to

North Africa North Africa, or Northern Africa is a region encompassing the northern portion of the African continent. There is no singularly accepted scope for the region, and it is sometimes defined as stretching from the Atlantic shores of Mauritania in ...

to study geology and terrestrial magnetism, and during this period published some important charts of the distribution of pressure at a height of 4,000 metres. Between 1892 and 1896, Teisserenc de Bort was chief meteorologist to the Bureau.

Instrumented balloons pioneer

After his resignation from the Bureau in 1896, he established a private meteorological observatory in

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near

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. There he carried out investigations on clouds and the problems of the upper air. He conducted experiments with high-flying instrumented

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

balloons and was one of the first people to use such devices. In 1898, Teisserenc de Bort published an important paper in ''Comptes Rendus'' detailing his researches by means of balloons into the constitution of the atmosphere. He noticed that while the air

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

decreased steadily up to approximately 11 kilometers of height, it remained constant above that

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

(up to the highest points he could reach). In other words, he discovered an indication of a

temperature inversion In meteorology, an inversion is a deviation from the normal change of an atmospheric property with altitude. It almost always refers to an inversion of the air temperature lapse rate, in which case it is called a temperature inversion. No ...

or at least of a zero lapse rate above this altitude. For many years he was uncertain whether he discovered a true

physical phenomenon A phenomenon ( : phenomena) is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which ''cannot'' be directly observed. Kant was heavily influenced by Gottfrie ...

or whether his measurements suffered from a systematic

bias Bias is a disproportionate weight ''in favor of'' or ''against'' an idea or thing, usually in a way that is closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individual, a group, ...

(indeed, the first measurements ''did'' have a positive temperature bias as the instruments were liable to radiative heating by

solar radiation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m ...

). 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 as the "

troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From ...

" and the "

". 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.

Additional investigations

He also carried out investigations near Viborg in Denmark 1902-1903,Léon Philippe Teisserenc de Bort, Hugo Hildebrand Hildebrandsson, H. Maurice, Ragnar Holm & Martin Jansson, ''Travaux de la Station Franco-Scandinave de Sondages Aériens à Hald 1902-1903'', 1904. in

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and over the

Zuider Zee The Zuiderzee or Zuider Zee (; old spelling ''Zuyderzee'' or ''Zuyder Zee'') was a shallow bay of the North Sea in the northwest of the Netherlands, extending about 100 km (60 miles) inland and at most 50 km (30 miles) wide, with an ov ...

, the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...

and the tropical region of the

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

, and fitted out a special vessel in order to study the currents above the

trade winds The trade winds or easterlies are the permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisph ...

. He was elected a fellow of the

Royal Meteorological Society The Royal Meteorological Society is a long-established institution that promotes academic and public engagement in weather and climate science. Fellows of the Society must possess relevant qualifications, but Associate Fellows can be lay enthus ...

in 1903, honorary member in 1909, and was awarded the

Symons Gold Medal The Symons Gold Medal is awarded biennially by the Royal Meteorological Society for distinguished work in the field of meteorological science. It was established in 1901 in memory of George James Symons, a notable British meteorologist. Recipients ...

of the Society in 1908. He collaborated with Hugo Hildebrandsson in ''Les bases de la météorologie dynamique'' (1907).

Named after him

* The crater Teisserenc on the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

. * The crater Teisserenc de Bort on

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...

References

External links

History of the Teisserenc de Bort observatory
{{DEFAULTSORT:Teisserenc De Bort, Leon 1855 births 1913 deaths Scientists from Paris French climatologists French meteorologists Members of the French Academy of Sciences Atmospheric sounding Members of the Royal Society of Sciences in Uppsala