[5] 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.

After returning from active service in the First World War, Appleton became assistant demonstrator in experimental physics at the Cavendish Laboratory in 1920.

Knighted in 1941, he received the 1947 Nobel Prize in Physics for his contributions to the knowledge of the ionosphere,[8] which led to the development of radar.

[9] From 1960 he was involved with the University's plans for a CDA (Comprehensive Development Area) which would have demolished 125 acres of Edinburgh's historic southside, resulting in the loss of many homes and businesses.

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.

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.

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 Arthur E. Kennelly had suggested such an electromagnetic-reflecting stratum, now called the Kennelly–Heaviside layer, 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.

[citation needed] 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.

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.

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.

In their experiment, they used the BBC broadcasting station in Bournemouth to vary the wavelengths of its emissions after the evening programmes had finished.

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.

The lower level was labelled E – Layer, reflected longer wavelengths and was found to be at approximately 78 miles (125 km).

It is this which is often referred to as the Appleton Layer as is responsible for enabling most long range short wave telecommunication.

[12] 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.

This means absorption rates diminish and waves can be reflected with sufficient strengths to be noticed, leading to the interference phenomena we have mentioned.

[citation needed] 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.

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.

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.