William Jackson Humphreys (February 3, 1862 – November 10, 1949) was an American physicist and atmospheric researcher.

Biography

Humphreys was born on February 3, 1862, in Gap Mills, West Virginia to Jackson and Eliza Ann (née Eads) Humphreys. He studied physics at

Washington & Lee University , mottoeng = "Not Unmindful of the Future" , established = , type = Private liberal arts university , academic_affiliations = , endowment = $2.092 billion (2021) , president = William C. Dudley , provost = Lena Hill , city = Lexing ...

in Virginia and later at

Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hem ...

in Baltimore, where he earned his Ph.D. in 1897, studying under

Henry Augustus Rowland Henry Augustus Rowland (November 27, 1848 – April 16, 1901) was an American physicist and Johns Hopkins educator. Between 1899 and 1901 he served as the first president of the American Physical Society. He is remembered primarily for the h ...

. He worked in the fields of

spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wa ...

atmospheric physics Within the atmospheric sciences, atmospheric physics is the application of physics to the study of the atmosphere. Atmospheric physicists attempt to model Earth's atmosphere and the atmospheres of the other planets using fluid flow equations, chem ...

and

meteorology Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did no ...

. In the field of spectroscopy he found the shift of

spectral lines A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identi ...

under

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and ...

. In atmospheric physics he found a very good model for 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 hi ...

in 1909. He wrote numerous books, including a textbook titled ''Physics of the Air'', first published in 1920 and considered a standard work of the time, though it was last published in 1940. He also held some teaching positions at universities. He concluded that the

1815 eruption of Mount Tambora Mount Tambora is a volcano on the island of Sumbawa in present-day Indonesia, then part of the Dutch East Indies, and its 1815 eruption was the most powerful volcanic eruption in recorded human history. This volcanic explosivity index (VEI) 7 ...

was responsible for the subsequent cooling known as the

Year Without a Summer The year 1816 is known as the Year Without a Summer because of severe climate abnormalities that caused average global temperatures to decrease by . Summer temperatures in Europe were the coldest on record between the years of 1766–2000. Thi ...

. From 1905 to 1935 he worked as a physicist for the U.S. Weather Bureau, predecessor of the

National Weather Service The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the ...

. In 1919, he served as President of the

Philosophical Society of Washington Founded in 1871, the Philosophical Society of Washington is the oldest scientific society in Washington, D.C. It continues today as PSW Science. Since 1887, the Society has met regularly in the assembly hall of the Cosmos Club. In the Club's pr ...

. In 1924 he was an Invited Speaker of the ICM in Toronto. He died on November 10, 1949, in

Washington, D.C. ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan, ...

Delegates to the Fourth Conference International Union for Cooperation in Solar Research at Mount Wilson Observatory

Bibliography

''Physics of the Air''
(1920)
''Weather proverbs and paradoxes''
(1923)
''Fogs and clouds''
The Williams & Wilins Co. (1926)
''Rain making and Other weather vagaries''
(1926) *''Snow crystals'' (1931)

References

{{DEFAULTSORT:Humphreys, William Jackson American physicists American meteorologists American people of Welsh descent 1862 births 1949 deaths Howard N. Potts Medal recipients Washington and Lee University alumni Johns Hopkins University alumni