Jacob Aall Bonnevie Bjerknes ( , ; 2 November 1897 – 7 July 1975) was a

meteorologist A meteorologist is a scientist who studies and works in the field of meteorology aiming to understand or predict Earth's atmosphere of Earth, atmospheric phenomena including the weather. Those who study meteorological phenomena are meteorologists ...

. He is known for his key paper in which he pointed the dynamics of the polar front, mechanism for north-south heat transport and for which he was also awarded a doctorate from the University of Oslo. Born in Stockholm, Sweden, he was the son of the Norwegian meteorologist Vilhelm Bjerknes, one of the pioneers of modern weather forecasting. He helped develop the Norwegian cyclone model. He earned a Ph.D. from the University of Oslo in 1924. Bjerknes was part of the team that made the first crossing of the Arctic in the airship Norge. During WWII, he helped the US with the planning of the Hiroshima and Nagasaki atomic bombings. He also helped gain an understanding of the weather phenomenon

El Niño EL, El or el may refer to: Arts and entertainment Fictional entities * El, a character from the manga series ''Shugo Chara!'' by Peach-Pit * Eleven (''Stranger Things'') (El), a fictional character in the TV series ''Stranger Things'' * El, fami ...

Background

Jacob Aall Bonnevie Bjerknes was born in

Stockholm, Sweden Stockholm (; ) is the Capital city, capital and List of urban areas in Sweden by population, most populous city of Sweden, as well as the List of urban areas in the Nordic countries, largest urban area in the Nordic countries. Approximately ...

. His father was the Norwegian meteorologist Vilhelm Bjerknes, one of the pioneers of modern weather forecasting. His paternal grandfather was Norwegian mathematician and physicist Carl Anton Bjerknes. His maternal grandfather was Norwegian politician Jacob Aall Bonnevie, after whom he was named.

Professional career

Bjerknes was part of a group of meteorologists led by his father, Vilhelm Bjerknes, at the

University of Leipzig Leipzig University (), in Leipzig in Saxony, Germany, is one of the world's oldest universities and the second-oldest university (by consecutive years of existence) in Germany. The university was founded on 2 December 1409 by Frederick I, Electo ...

. Together they developed the model that explains the generation, intensification and ultimate decay (the life cycle) of mid-latitude cyclones, introducing the idea of fronts, that is, sharply defined boundaries between air masses. This concept is known as the Norwegian cyclone model. Bjerknes returned to Norway in 1917, where his father founded the Geophysical Institute, University of Bergen in

Bergen Bergen (, ) is a city and municipalities of Norway, municipality in Vestland county on the Western Norway, west coast of Norway. Bergen is the list of towns and cities in Norway, second-largest city in Norway after the capital Oslo. By May 20 ...

. They organized an analysis and forecasting branch which would evolve into a weather bureau by 1919. The scientific team at Bergen also included the Swedish meteorologists Carl-Gustaf Rossby and Tor Bergeron. As pointed out in a key paper by Jacob Bjerknes and Halvor Solberg (1895-1974) in 1922, the dynamics of the polar front, integrated with the cyclone model, provided the major mechanism for north-south heat transport in the atmosphere. For this and other research, Jacob Bjerknes was awarded the Ph.D. from the

University of Oslo The University of Oslo (; ) is a public university, public research university located in Oslo, Norway. It is the List of oldest universities in continuous operation#Europe, oldest university in Norway. Originally named the Royal Frederick Univ ...

in 1924.''Halvor Solberg''
(Store norske leksikon) In 1926, Jacob Bjerknes was a support meteorologist when

Roald Amundsen Roald Engelbregt Gravning Amundsen (, ; ; 16 July 1872 – ) was a Norwegians, Norwegian explorer of polar regions. He was a key figure of the period known as the Heroic Age of Antarctic Exploration. Born in Borge, Østfold, Norway, Am ...

made the first crossing of the Arctic in the airship Norge. In 1931, he left his position as head of the National weather service at Bergen to become professor of meteorology at the Geophysical Institute at the University of Bergen. Jacob Bjerknes lectured at the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

during the 1933-1934 school year. In 1940, he emigrated to the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, where he headed a government-sponsored meteorology annex for weather forecasting, at the department of physics of the

University of California, Los Angeles The University of California, Los Angeles (UCLA) is a public university, public Land-grant university, land-grant research university in Los Angeles, California, United States. Its academic roots were established in 1881 as a normal school the ...

. During the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

Bjerknes was in the

US armed forces The United States Armed Forces are the military forces of the United States. U.S. federal law names six armed forces: the Army, Marine Corps, Navy, Air Force, Space Force, and the Coast Guard. Since 1949, all of the armed forces, except ...

, and serving as a colonel in the US Air Force he helped determine the best dates for the

atomic bombings of Hiroshima and Nagasaki On 6 and 9 August 1945, the United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki, respectively, during World War II. The aerial bombings killed between 150,000 and 246,000 people, most of whom were civili ...

. Bjerknes founded the

UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California, United States. Its academic roots were established in 1881 as a normal school then known as the southern branch of the C ...

Department of Meteorology (now the Department of Atmospheric and Oceanic Sciences). As a professor at the University of California, he was the first to see a connection between unusually warm sea-surface temperatures and the weak easterlies and heavy rainfall that accompany . At UCLA, Bjerknes and fellow Norwegian-American meteorologist, Jorgen Holmboe, further developed the pressure tendency and the

extratropical cyclone Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of p ...

theories. In 1969, Jacob Bjerknes helped toward an understanding of

Southern Oscillation, by suggesting that an anomalously warm spot in the eastern Pacific can weaken the east-west temperature difference, disrupting trade winds, which push warm water to the west. The result is increasingly warm water toward the east.

Personal life

In 1928, he married Hedvig Borthen (1904–1998). They were the parents of two children. He died on 7 July 1975 in

Los Angeles, California Los Angeles, often referred to by its initials L.A., is the List of municipalities in California, most populous city in the U.S. state of California, and the commercial, Financial District, Los Angeles, financial, and Culture of Los Angeles, ...

Honors and awards

He was made an Honorary Member of the

Royal Meteorological Society The Royal Meteorological Society is an organization that promotes academic and public engagement in weather and climate science. Fellows of the Society must possess relevant qualifications, but Members can be lay enthusiasts. It publishes vari ...

in 1932 and a member of both the

Norwegian Academy of Science and Letters The Norwegian Academy of Science and Letters (, DNVA) is a learned society based in Oslo, Norway. Its purpose is to support the advancement of science and scholarship in Norway. History The Royal Frederick University in Christiania was establis ...

and the Royal Swedish Academy of Science in 1933. *

- Symons Gold Medal (1940) *

American Geophysical Union The American Geophysical Union (AGU) is a 501(c)(3) nonprofit organization of Earth, Atmospheric science, atmospheric, Oceanography, ocean, Hydrology, hydrologic, Astronomy, space, and Planetary science, planetary scientists and enthusiasts that ...

- William Bowie Medal (1945) * Knight 1st Class of the Royal Norwegian Order of St. Olav (1947). * Swedish Society for Anthropology and Geography - Vega medal (1958) *

World Meteorological Organization The World Meteorological Organization (WMO) is a List of specialized agencies of the United Nations, specialized agency of the United Nations responsible for promoting international cooperation on atmospheric science, climatology, hydrology an ...

- International Meteorological Organization Prize (1959). *

American Meteorological Society The American Meteorological Society (AMS) is a scientific and professional organization in the United States promoting and disseminating information about the atmospheric, oceanic, and hydrologic sciences. Its mission is to advance the atmosph ...

- Carl-Gustaf Rossby Research Medal (1960) *

National Medal of Science The National Medal of Science is an honor bestowed by the President of the United States to individuals in science and engineering who have made important contributions to the advancement of knowledge in the fields of behavioral science, behavior ...

(1966) *

American Academy of Achievement The American Academy of Achievement, colloquially known as the Academy of Achievement, is a nonprofit educational organization that recognizes some of the highest-achieving people in diverse fields and gives them the opportunity to meet one ano ...

- Golden Plate Award (1967)

References

External links

Biographie de Jacob Bjerknes
by Arnt Eliassen
Tribute to J. Bjerknes on the 100th anniversary of his birthJacob Bjerknes photographNational Academy of Sciences Biographical Memoir
{{DEFAULTSORT:Bjerknes, Jacob 1897 births 1975 deaths National Medal of Science laureates Norwegian meteorologists Norwegian climatologists Carl-Gustaf Rossby Research Medal recipients Norwegian emigrants to the United States Members of the Norwegian Academy of Science and Letters Recipients of the St. Olav's Medal Jakob Bonnevie family