= Edward Victor Appleton
{c}
{tag=Physicist}
{title2=1892–1965}
{wiki}
= Edward V. Appleton
{c}
{synonym}
= E. V. Appleton
{c}
{synonym}
= Edward Appleton
{c}
{synonym}
<Edward Victor Appleton> investigated the <ionosphere> by measuring how radio signals return from the upper <atmosphere>. Comparing direct and returning <radio waves> makes their path difference experimentally accessible and constrains the effective height of the reflecting region.
The response changes with <frequency> because the atmosphere's free <electrons> alter electromagnetic propagation. Scanning <frequency> and observing the returning signals helps distinguish ionized layers and their changing conditions. His Nobel lecture connects these measurements with the physical basis of long-distance radio propagation.<The Ionosphere by Edward Victor Appleton>[Nobel lecture: reflected radio signals, effective heights, critical frequencies and ionized layers]{ref}
\Image[https://commons.wikimedia.org/wiki/Special:Redirect/file/Appleton.jpg?width=250]
{title=Portrait of <Edward Victor Appleton>}
{description=Nobel Foundation, portrait dated 1947; individual photographer unspecified. https://commons.wikimedia.org/wiki/File:Appleton.jpg[Commons asserts Swedish-photograph public-domain status and additionally records a United States PD-1996/URAA public-domain claim.], via Wikimedia Commons.}
{source=https://commons.wikimedia.org/wiki/File:Appleton.jpg}
{width=250}
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