John Aitken (scientist)
Encyclopedia
John Aitken FRS
FRS
-Education:* Frontier Regional School, a regional school located in South Deerfield, Massachusetts-Government:*FRS 567 states that, an accountant shall perfom his/ her duty with due care...

 FRSE (1839–1919) was a Scottish meteorologist, physicist and marine engineer. He was one of the founders of cloud physics
Cloud physics
Cloud physics is the study of the physical processes that lead to the formation, growth and precipitation of clouds. Cloud formations are composed of microscopic droplets of liquid water , tiny crystals of ice , or both...

 and aerosol science
Aerosol science
Aerosol science is the rapidly expanding field of science which investigates the physical, chemical, and biological properties of aerosolized materials , which behave in ways that make them unique from even other forms of similar materials...

, who built the first apparatus to measure the number of dust and fog particles in the atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

, a koniscope
Koniscope
A Koniscope is a scientific instrument to detect and measure content of dust particles in the atmosphere. A koniscope is also called dust counter, or Aitken dust counter, named after John Aitken who invented the first koniscope....

. One of his experiments conducted with a self-designed apparatus provided the first evidence of new particle formation in the atmosphere. This work was documented in an article titled On some nuclei of cloudy condensation
Cloud condensation nuclei
Cloud condensation nuclei or CCNs are small particles typically 0.2 µm, or 1/100 th the size of a cloud droplet ) about which cloud droplets coalesce. Water requires a non-gaseous surface to make the transition from a vapour to a liquid. In the atmosphere, this surface presents itself as tiny...

, in the 39th volume of the Transactions of the Royal Society of Edinburgh
Royal Society of Edinburgh
The Royal Society of Edinburgh is Scotland's national academy of science and letters. It is a registered charity, operating on a wholly independent and non-party-political basis and providing public benefit throughout Scotland...

 published in 1898.

John Aitken was the author of a number of important pioneering discoveries "On Dust, Fogs and Clouds" (The title of an 1880 article he penned). As early as 1874, Aitken had concluded that when water vapor in the atmosphere condenses, it must condense on some solid particle, and thus, without the presence of dust and other aerosol particles in the air, there would be no formation of fog, clouds, or rain. In 1884, he concluded that the brilliant colors often seen in the sunset are due to the refraction of light by dust particles in the upper atmosphere. In 1889 Aitken was elected a Fellow of the Royal Society and in 1917, he was awarded the Royal Medal
Royal Medal
The Royal Medal, also known as The Queen's Medal, is a silver-gilt medal awarded each year by the Royal Society, two for "the most important contributions to the advancement of natural knowledge" and one for "distinguished contributions in the applied sciences" made within the Commonwealth of...

 of the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

.

Today, his name is given by atmospheric scientists to the smallest atmospheric aerosol
Aerosol
Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...

 particles (Aitken nuclei), those with a radius less than 0.1 micrometers. This size range include the newly nucleated
Nucleation
Nucleation is the extremely localized budding of a distinct thermodynamic phase. Some examples of phases that may form by way of nucleation in liquids are gaseous bubbles, crystals or glassy regions. Creation of liquid droplets in saturated vapor is also characterized by nucleation...

 particles whose existence Aitken demonstrated.

Early life

Aitken was born in Falkirk
Falkirk
Falkirk is a town in the Central Lowlands of Scotland. It lies in the Forth Valley, almost midway between the two most populous cities of Scotland; north-west of Edinburgh and north-east of Glasgow....

 on 18 September 1839, the son of Henry Aitken of Darroch, a Falkirk lawyer. He was educated at Falkirk Grammar School and studied marine engineering
Naval architecture
Naval architecture is an engineering discipline dealing with the design, construction, maintenance and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation and calculations during all stages of the life of a...

 at Glasgow University, undertaking his engineer training with Messrs Napier & Sons, the Glasgow shipbuilder.

External links

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