Edward Victor Appleton

Sir Edward Victor Appleton GBE KCB FRS[3] (6 September 1892 – 21 April 1965) was an English physicist,[4][5] Nobel Prize winner (1947) and pioneer in radiophysics. He studied, and was also employed as a lab technician, at Bradford College from 1909 to 1911.

He won the Nobel Prize in Physics in 1947 for his seminal work proving the existence of the ionosphere during experiments carried out in 1924.

Edward Victor Appleton
Appleton
Born6 September 1892
Died21 April 1965 (aged 72)
NationalityEnglish
Alma materSt John's College, Cambridge
Known forIonospheric Physics[1][2]
Appleton layer
Demonstrating existence of Kennelly–Heaviside layer
AwardsNobel Prize in Physics (1947)
Fellow of the Royal Society (1927)[3]
Hughes Medal (1933)
Faraday Medal (1946)
Chree Medal (1947)
Royal Medal (1950)
Albert Medal (1950)
IEEE Medal of Honor (1962)
Scientific career
FieldsPhysics
InstitutionsBradford College
King's College London
University of Cambridge
University of Edinburgh
Cavendish Laboratory
Academic advisorsJ. J. Thomson
Ernest Rutherford
Notable studentsJ. A. Ratcliffe
Charles Oatley
The grave of Sir Edward Victor Appleton, Morningside Cemetery, Edinburgh
The grave of Sir Edward Victor Appleton, Morningside Cemetery, Edinburgh

Biography

Appleton was born in Bradford, West Riding of Yorkshire, the son of Peter Appleton, a warehouseman, and Mary Wilcock,[6] and was educated at Hanson Grammar School.

In 1911, aged 18, he was awarded a scholarship to attend St John’s College, Cambridge, where he graduated with First Class Honours in Natural Science with Physics in 1913.

During the First World War he joined the West Riding Regiment, and later transferred to the Royal Engineers. After returning from active service in the First World War, Appleton became assistant demonstrator in experimental physics at the Cavendish Laboratory in 1920. In 1922 he was initiated into Freemasonry[7]. He was professor of physics at King's College London (1924–36) and professor of natural philosophy at the University of Cambridge (1936–39). From 1939 to 1949 he was secretary of the Department of Scientific and Industrial Research. Knighted in 1941, he received the 1947 Nobel Prize in Physics for his contributions to the knowledge of the ionosphere,[2] which led to the development of radar.

From 1949 until his death in 1965, Appleton was Principal and Vice-Chancellor of the University of Edinburgh.[8] In 1956, the BBC invited him to deliver the annual Reith Lectures. Across a series of six radio broadcasts, titled Science and the Nation, he explored the many facets of scientific activity in Britain at the time.

Sir Edward is buried in Edinburgh's Morningside Cemetery[9] with his wife Helen Lennie (d. 1983). The grave lies towards the extreme western side near the new housing to the north-west.

Works

Appleton had observed that the strength of the radio signal from a transmitter on a frequency such as the medium wave band and over a path of a hundred miles or so was constant during the day but that it varied during the night. This led him to believe that it was possible that two radio signals were being received. One was travelling along the ground, and another was reflected by a layer in the upper atmosphere. The fading or variation in strength of the overall radio signal received resulted from the interference pattern of the two signals.

The existence of a reflecting atmospheric layer was not in itself a completely new idea. Balfour Stewart had suggested the idea in the late 19th century to explain rhythmic changes in the earth’s magnetic field. More recently, in 1902, Oliver Heaviside and A. E. Kennelly had suggested such a hypothesis may explain the success Marconi had in transmitting his signals across the Atlantic. Calculations had shown that natural bending of the radio waves was not sufficient to stop them from simply “shooting off” into empty space before they reached the receiver.

Appleton thought the best place to look for evidence of the ionosphere was in the variations he believed it was causing around sunset in radio signal receptions. It was sensible to suggest these variations were due to the interference of two waves but an extra step to show that the second wave causing the interference (the first being the ground wave) was coming down from the ionosphere. The experiment he designed had two methods to show ionospheric influence and both allowed the height of the lower boundary of reflection (thus the lower boundary of the reflecting layer) to be determined. The first method was called frequency modulation and the second was to calculate the angle of arrival of the reflected signal at the receiving aerial.

The frequency modulation method exploits the fact that there is a path difference between the ground wave and the reflected wave, meaning they travel different distances from sender to receiver.

Let the distance AC travelled by the ground wave be h and the distance ABC travelled by the reflected wave h’. The path difference is:

The wavelength of the transmitted signal is λ. The number of wavelengths difference between the paths h and h’ is:

If N is an integer number, then constructive interference will occur, this means a maximum signal will be achieved at the receiving end. If N is an odd integer number of half wavelengths, then destructive interference will occur and a minimum signal will be received. Let us assume we are receiving a maximum signal for a given wavelength λ. If we start to change λ, this is the process called frequency modulation, N will no longer be a whole number and destructive interference will start to occur, meaning the signal will start to fade. Now we keep changing λ until a maximum signal is once again received. The means that for our new value λ’, our new value N’ is also an integer number. If we have lengthened λ then we know that N’ is one less than N. Thus:

Rearranging for D gives:

As we know λ and λ’, we can calculate D. Using the approximation that ABC is an isosceles triangle, we can use our value of D to calculate the height of the reflecting layer. This method is a slightly simplified version of the method used by Appleton and his colleagues to work out a first value for the height of the ionosphere in 1924. In their experiment, they used the BBC broadcasting station in Bournemouth to vary the wavelengths of its emissions after the evening programmes had finished. They installed a receiving station in Oxford to monitor the interference effects. The receiving station had to be in Oxford as there was no suitable emitter at the right distance of about 62 miles (100 km) from Cambridge in those days.

This frequency modulation method revealed that the point from which waves were being reflected was approximately 56 miles (90 km). However, it did not establish that the waves were reflected from above, indeed they may have been coming from hills somewhere between Oxford and Bournemouth. The second method, which involved finding the angle of incidence of the reflected waves at the receiver, showed for sure that they were coming from above. Triangulations from this angle gave results for the height of reflection compatible with the frequency modulation method. We will not go into this method in detail because it involves fairly complex calculations using Maxwell’s electromagnetic theory.

Far from being conclusive, the success of the Oxford-Bournemouth experiment revealed a vast new field of study to be explored. It showed that there was indeed a reflecting layer high above the earth but it also posed many new questions. What was the constitution of this layer, how did it reflect the waves, was it the same all over the earth, why did its effects change so dramatically between day and night, did it change throughout the year? Appleton would spend the rest of his life answering these questions. He developed a magneto-ionic theory based on the previous work of Lorentz and Maxwell to model the workings of this part of the atmosphere. Using this theory and further experiments, he showed that the so-called Kennelly-Heaviside layer was heavily ionised and thus conducting. This led to the term ionosphere. He showed free electrons to be the ionising agents. He discovered that the layer could be penetrated by waves above a certain frequency and that this critical frequency could be used to calculate the electron density in the layer. However these penetrating waves would also be reflected back, but from a much higher layer. This showed the ionosphere had a much more complex structure than first anticipated. The lower level was labelled E – Layer, reflected longer wavelengths and was found to be at approximately 78 miles (125 km). The high level, which had much higher electron density, was labelled F – Layer and could reflect much shorter wavelengths that penetrated the lower layer. It is situated 186 – 248 miles (300 – 400 km) above the earth’s surface. It is this which is often referred to as the Appleton Layer as is responsible for enabling most long range short wave telecommunication.[10]

The magneto-ionic theory also allowed Appleton to explain the origin of the mysterious fadings heard on the radio around sunset. During the day, the light from the sun causes the molecules in the air to become ionised even at fairly low altitudes. At these low altitudes, the density of the air is great and thus the electron density of ionised air is very large. Due to this heavy ionisation, there is strong absorption of electromagnetic waves caused by ‘electron friction’. Thus in transmissions over any distance, there will be no reflections as any waves apart from the one at ground level will be absorbed rather than reflected. However, when the sun sets, the molecules slowly start to recombine with their electrons and the free electron density levels drop. This means absorption rates diminish and waves can be reflected with sufficient strengths to be noticed, leading to the interference phenomena we have mentioned. For these interference patterns to occur though, there must not simply be the presence of a reflected wave but a change in the reflected wave. Otherwise the interference is constant and fadings would not be heard. The received signal would simply be louder or softer than during the day. This suggests the height at which reflection happens must slowly change as the sun sets. Appleton found in fact that it increased as the sun set and then decreased as the sun rose until the reflected wave was too weak to record. This variation is compatible with the theory that ionisation is due to the sun’s influence. At sunset, the intensity of the sun’s radiation will be much less at the surface of the earth than it is high up in the atmosphere. This means ionic recombination will progress slowly from lower altitudes to higher ones and therefore the height at which waves are reflected slowly increases as the sun sets.

The basic idea behind Appleton’s work is so simple that it is hard to understand at first how he devoted almost all of his scientific career to its study. However, in the last couple of paragraphs some of the complexities of the subject have been introduced. Like many other fields, it is one that grows in intricacy the more it is studied. By the end of his life, ionospheric observatories had been set up all over the world to provide a global map of the reflecting layers. Links were found to the 11 year sunspot cycle and the Aurora Borealis, the magnetic storms that occur in high latitudes. This became particularly relevant during the Second World War when the storms would lead to radio blackouts. Thanks to Appleton’s research, the periods when these would occur could be predicted and communication could be switched to wavelengths that would be least affected. Radar, another crucial wartime innovation, was one that came about thanks to Appleton’s work. On a very general level, his research consisted in determining the distance of reflecting objects from radio signal transmitters. This is exactly the idea of radar and the flashing dots that appear on the screen (a cathode ray tube) scanned by the circulating ‘searcher’ bar. This system was developed partly by Appleton as a new method, called the pulse method, to make ionospheric measurements. It was later adapted by Robert Watson-Watt to detect aeroplanes. Nowadays, ionospheric data is important when communications with satellites are considered. The correct frequencies for these signals must be selected so that they actually reach the satellites without being reflected or deviated before.

In 1974 the Radio and Space Research Station was renamed the Appleton Laboratory in honour of the man who had done so much to establish the UK as a leading force in ionospheric research, and had been involved with the station first as a researcher and then as secretary of its parent body, the Department of Scientific and Industrial Research.

Honours and awards

Appleton was awarded the following:

In addition the following are named in his honour:

Artistic recognition

Appleton's portrait, by William Hutchison hangs in Old College, University of Edinburgh.

See also

References

  1. ^ Appleton, E. V. (1946). "Two Anomalies in the Ionosphere". Nature. 157 (3995): 691. Bibcode:1946Natur.157..691A. doi:10.1038/157691a0.
  2. ^ a b Appleton, EV (1932). "Wireless Studies of the Ionosphere". J. Inst. Elec. Engrs. doi:10.1049/jiee-1.1932.0144.
  3. ^ a b c Ratcliffe, J. A. (1966). "Edward Victor Appleton 1892–1965". Biographical Memoirs of Fellows of the Royal Society. 12: 1–19. doi:10.1098/rsbm.1966.0001.
  4. ^ "Sir Edward Appleton (1892–1965)".
  5. ^ "Sir Edward Appleton". Physics Today. 18 (9): 113. 1965. doi:10.1063/1.3047706.
  6. ^ http://www.royalsoced.org.uk/cms/files/fellows/biographical_index/fells_indexp1.pdf
  7. ^ http://freemasonry.london.museum/it/wp-content/resources/frs_freemasons_complete_jan2010.pdf
  8. ^ Lister, Derek A J (2004). Bradford's Own. Sutton. ISBN 0-7509-3826-9.
  9. ^ Sir Edward Victor Appleton at Find a Grave
  10. ^ IEEE Global History Network (2011). "Edward V. Appleton". IEEE History Center. Retrieved 14 July 2011.
  11. ^ "Book of Members, 1780–2010: Chapter A" (PDF). American Academy of Arts and Sciences. Retrieved 19 April 2011.

External links

Academic offices
Preceded by
Sir John Fraser
Principals of Edinburgh University
1948–1965
Succeeded by
Michael Swann
1892

1892 (MDCCCXCII)

was a leap year starting on Friday of the Gregorian calendar and a leap year starting on Wednesday of the Julian calendar, the 1892nd year of the Common Era (CE) and Anno Domini (AD) designations, the 892nd year of the 2nd millennium, the 92nd year of the 19th century, and the 3rd year of the 1890s decade. As of the start of 1892, the Gregorian calendar was

12 days ahead of the Julian calendar, which remained in localized use until 1923.

1892 in the United Kingdom

Events from the year 1892 in the United Kingdom.

Appleton (surname)

Appleton is an Anglo-Saxon locational surname.

Alistair Appleton, British television presenter

Charles Appleton (academic) (1841–1879), Oxford don and scholarly entrepreneur

Charles Appleton (cricketer) (1844–1925), English amateur cricketer

Charles William Appleton (1874–1945), vice president of the General Electric Company, judge and Assistant District Attorney in New York City

Colin Appleton, footballer

Daniel Appleton, American publisher, 1800s founder of D. Appleton & Company

Edward Victor Appleton, English physicist, known for his research on the ionosphere

Edwin Nelson Appleton, American Medal of Honor recipient

Francis R. Appleton (1854–1929), lawyer and member of the 400 during the Gilded Age

Frankie A Appleton (1998–2017), footballer

George Swett Appleton (1821–1878), American publisher

Henry Appleton (fl. 1650–1654), English captain in the navy and commodore

James Appleton (1786-1862), American abolitionist

John Appleton, American diplomat, politician, and newspaper editor

John Appleton (academic), Master of University College, Oxford, England (c.1401–8)

John E. C. Appleton (1905–1990), Australian theatre and radio producer

John F. Appleton (1838–1870), American Civil War general from Maine

John Howard Appleton, American chemist

John James Appleton (1789–1864), diplomat for the United States

Jon Appleton, American composer, author and professor of music

Larry Appleton, a character from the TV series Perfect Strangers

Michael Appleton, footballer

Natalie Appleton, British/Canadian singer

Nathan Appleton, American merchant and politician

Nicole Appleton, British/Canadian singer

Ray Appleton (1941–2015), American jazz drummer

Ruel Ross Appleton (1853–1928), campaign manager for Mayor Gaynor of New York City

Samuel Appleton (1766–1853), an American merchant and philanthropist

Scott Appleton (1942-1992), American football player

Thomas Gold Appleton (1812–1884), American author and artist

Victor Appleton, a house pseudonym, famous for the Tom Swift series

William Appleton (politician) (1786–1862), congressman from Massachusetts

Will Appleton (1889–1958), mayor of Wellington, New Zealand

William Sumner Appleton (1874–1947), founder of the Society for the Preservation of New England Antiquities

William M. Appleton (1920–2001), Pennsylvania politician

William Henry Appleton (1814–1899), American publisher

William Appleton (entrepreneur) (born 1961), American entrepreneur and technologist

William H. Appleton (1843–1912), American soldier and Medal of Honor recipient

William Thomas Appleton (1859–1930), Australian businessman, shipping agent and public servant

Appleton Academy

Appleton Academy is a mixed all-through school for pupils aged 3 to 19. It is located in Wyke in the City of Bradford, in the English county of West Yorkshire. The school is named after Sir Edward Victor Appleton, a physicist who won the Nobel Prize in Physics in 1947.

The school was formed in 2009 from the merger of Wyke Manor School (secondary school) and High Fernley Primary School. The school moved into new buildings in 2012. It is an academy that is sponsored by Bradford College as part of the Bradford College Education Trust.

Appleton Academy offers GCSEs as programmes of study for pupils, while students in the sixth form have the option to study from a range of A-levels and BTECs. The school also has specialisms in science and sport.

Appleton–Hartree equation

The Appleton–Hartree equation, sometimes also referred to as the Appleton–Lassen equation is a mathematical expression that describes the refractive index for electromagnetic wave propagation in a cold magnetized plasma. The Appleton–Hartree equation was developed independently by several different scientists, including Edward Victor Appleton, Douglas Hartree and German radio physicist H. K. Lassen. Lassen's work, completed two years prior to Appleton and five years prior to Hartree, included a more thorough treatment of collisional plasma; but, published only in German, it has not been widely read in the English speaking world of radio physics. Further, regarding the derivation by Appleton, it was noted in the historical study by Gilmore that Wilhelm Altar (while working with Appleton) first calculated the dispersion relation in 1926.

Edward Appleton

Edward Appleton may refer to:

Edward Victor Appleton (1892–1965), English physicist

Ed Appleton (1892–1932), American baseball player

Granville Beynon

Sir William John Granville Beynon, CBE, FRS (24 May 1914 in Dunvant – 11 March 1996 in Aberystwyth) was a Welsh physicist. He co-operated with Sir Edward Victor Appleton, who had detected the terrestrial Ionosphere.

IEEE Medal of Honor

The IEEE Medal of Honor is the highest recognition of the Institute of Electrical and Electronics Engineers (IEEE). It has been awarded since 1917, when its first recipient was Major Edwin H. Armstrong. It is given for an exceptional contribution or an extraordinary career in the IEEE fields of interest. The award consists of a gold medal, bronze replica, certificate and honorarium. The Medal of Honor may only be awarded to an individual.

The medal was created by the Institute of Radio Engineers (IRE) as the IRE Medal of Honor. It became the IEEE Medal of Honor when IRE merged with the American Institute of Electrical Engineers (AIEE) to form the IEEE in 1963. It was decided that IRE's Medal of Honor would be presented as IEEE's highest award, while the Edison Medal would become IEEE's principal medal.

Ten persons with an exceptional career in electrical engineering received both the IEEE Edison Medal and the IEEE Medal of Honor, namely Edwin Howard Armstrong, Ernst Alexanderson, Mihajlo Pupin, Arthur E. Kennelly, Vladimir K. Zworykin, John R. Pierce, Sidney Darlington, Nick Holonyak, Robert H. Dennard, Dave Forney, and Kees Schouhamer Immink.

IET Faraday Medal

The Faraday Medal is the top medal awarded by the Institution of Engineering and Technology (IET) (previously called the Institution of Electrical Engineers). It is part of the IET Achievement Medals collection of awards. The medal is named after the famous Michael Faraday FRS, the father of electromagnetism. Faraday is widely recognized as a top scientist, engineer, chemist, and inventor. His electromagnetic induction principles have been widely used in electric motors and generators today.

Institute of Physics Edward Appleton Medal and Prize

The Edward Appleton Medal and Prize is awarded by the Institute of Physics for distinguished research in environmental, earth or atmospheric physics. Originally named after Dr. Charles Chree, it was renamed in 2008 to commemorate Edward Victor Appleton. Established in 1941, the prize is currently awarded in even-dated years.

Ionosonde

An ionosonde, or chirpsounder, is a special radar for the examination of the ionosphere. The basic ionosonde technology was invented in 1925 by Gregory Breit and Merle A. Tuve and further developed in the late 1920s by a number of prominent physicists, including Edward Victor Appleton. The term ionosphere and hence, the etymology of its derivatives, was proposed by Robert Watson-Watt.

Journal of Atmospheric and Solar-Terrestrial Physics

The Journal of Atmospheric and Solar-Terrestrial Physics is a monthly peer-reviewed scientific journal covering the atmospheric and earth sciences. It was established in 1950 as the Journal of Atmospheric and Terrestrial Physics, obtaining its current name in 1997. It is published by Elsevier and sponsored by the International Union of Radio Science. According to the Journal Citation Reports, the journal has a 2013 impact factor of 1.751. Its founding editor was Edward Victor Appleton, and the current editors are R.J. Strangeway and D. Pancheva.

Kelvin Gold Medal

The Kelvin Gold Medal is a British engineering prize.

In the annual report for 1914, it was reported that the Lord Kelvin Memorial Executive Committee decided that the balance of funds left over from providing a memorial window at Westminster Abbey should be devoted to provide a Kelvin Gold Medal to mark "a distinction in engineering work or investigation" by the Presidents of eight leading British Engineering Institutions. There was a delay in awarding the first medal, due to the World War.

The medal has been given triennially since 1920 for "distinguished service in the application of science to engineering". The prize is administered by the Institution of Civil Engineers (Great Britain). The Committee of Presidents considers recommendations received from similar bodies from all parts of the world. The first recipient was William Unwin.

List of Nobel laureates affiliated with the University of Edinburgh

This list of Nobel laureates affiliated with the University of Edinburgh comprehensively shows the alumni, faculty members as well as researchers of the University of Edinburgh who were awarded the Nobel Prize and the Nobel Memorial Prize in Economic Sciences. The Nobel Prizes, established by the 1895 will of Alfred Nobel, are awarded to individuals who make outstanding contributions in the fields of Chemistry, Literature, Peace, Physics, and Physiology or Medicine. An associated prize, the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel (commonly known as the Nobel Prize in Economics), was instituted by Sweden's central bank, Sveriges Riksbank, in 1968 and first awarded in 1969.As of 2018, 19 Nobel laureates have been affiliated with the University of Edinburgh as alumni, faculty members and researchers. Among the laureates, 6 are Edinburgh alumni (graduates and attendees) and 5 have been long-term academic members of the Edinburgh faculty. Three additional laureates had acted as administrative staff of the university. However, the University of Edinburgh also claim one exchange student (Randy W Schekman), one honorary graduate (Malala Yousafzai), as well as four people who worked in Nobel-winning organizations as Nobel affiliates of the university, making a total of 28 affiliates.

List of Principals of the University of Edinburgh

Principals of the University of Edinburgh

1586 Robert Rollock (previously Regent)

1599 Henry Charteris

1620 Patrick Sands

1622 Robert Boyd

1623 John Adamson (died in office in 1652 but successor unable to take position until 1653 since the original choice, William Colvill was unable to take up the position)

1653 Robert Leighton

1662 William Colvill

1675 Andrew Cant

1685 Alexander Monro

1690 Gilbert Rule

1703 William Carstares

1716 William Wishart (primus)

1730 William Hamilton

1732 James Smith

1736 William Wishart (secundus)

1754 John Gowdie

1762 William Robertson

1793 George Husband Baird

1840 John Lee

1859 David Brewster

1868 Alexander Grant

1885 William Muir

1903 William Turner

1916 Alfred Ewing

1929 Thomas Henry Holland

1944 John Fraser

1948 Edward Victor Appleton

1965 Michael Swann

1974 Hugh Robson

1979 John Harrison Burnett

1987 David Smith

1994 Stewart Sutherland

2002 Timothy O'Shea

2018 Peter Mathieson

Mullard Radio Astronomy Observatory

The Mullard Radio Astronomy Observatory (MRAO) is located near Cambridge, UK and is home to a number of the largest and most advanced aperture synthesis radio telescopes in the world, including the One-Mile Telescope, 5-km Ryle Telescope, and the Arcminute Microkelvin Imager. It was founded by the University of Cambridge and is an institute of the Cambridge University Astronomy Department.

Radio Research Station (UK)

The Radio Research Board was formed by the Department of Scientific and Industrial Research in 1920. The Radio Research Station (1924 – 31 August 1979) at Ditton Park, Near Slough, Berkshire, England was the UK government research laboratory which pioneered the regular observation of the ionosphere by ionosondes. In continuous operation from 20 September 1932, it applied the ionosonde technology for the early developments which led to the British Chain Home radar system, operational during World War II.In 1965, it was renamed the Radio and Space Research Station, to reflect its increasing role in space research. In 1974, it became the Appleton Laboratory, in honour of Sir Edward Victor Appleton, who had received the 1947 Nobel prize for his work on the ionosphere and who had long been associated with the station's research. In 1979, the laboratory merged with the Rutherford Laboratory to form the Rutherford Appleton Laboratory and over the next three years moved from Ditton Park to Chilton, Oxfordshire.

University of Edinburgh School of Physics and Astronomy

The University of Edinburgh School of Physics and Astronomy is the physics department of the University of Edinburgh. The school was formed in 1993 by a merger of the Department of Physics - called the Department of Natural Philosophy until the late 1960s - and the Department of Astronomy, both at the University of Edinburgh. The school is part of the University's College of Science and Engineering.

1901–1925
1926–1950
1951–1975
1976–2000
2001–
present
1951–1975

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