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(1787–1826), German optician and pioneer in spectroscopy. He observed and mapped the dark lines in the solar spectrum (Fraunhofer lines) which result from the absorption of particular frequencies of light by elements present in the outer layers; these are now used to determine the chemical composition of the sun and stars.
- ‘The existence of the Fraunhofer lines is direct evidence that the temperature in the Sun's atmosphere decreases with height above the photosphere.’
- ‘Filling in of the Fraunhofer line as a function of altitude is used for cloud height analysis and to improve the retrieval of total column ozone.’
- ‘Measurement of luminescence using Fraunhofer lines typically involves observing a non-fluorescent material such as a halon or spectralon standard, and the target fluorescent material, at the center of the Fraunhofer line, and at the continuum, a few Angstroms from the line.’
- ‘The main goal is to develop an efficient sampling system on a long-term and continuous basis for the estimation of the primary productivity by measuring the chlorophyll solar induced fluorescence using the Fraunhofer line depth principle.’
- ‘These missing wavelengths, which appear as many thin dark lines, are called Fraunhofer lines and are caused by the atmosphere of the sun absorbing some of the light which the sun's surface is producing.’
- ‘A selected portion of each wing of the Fraunhofer line is imaged on the cathode of a corresponding photomultiplier.’
- ‘Herschel considered that the Fraunhofer lines could either be caused by absorption in a cool gas in the earth's or in the sun's atmosphere.’
- ‘We are shown clearly the bands of colors, but Rowland's more exacting analysis would spread this spectrum over sixty feet, revealing also the Fraunhofer lines: hundreds of dark lines interspersed throughout the spectrum.’
- ‘He independently rediscovered William Hyde Wollaston's dark lines in the solar spectrum, which are now known as Fraunhofer lines.’
- ‘The value of the Doppler shift and the shape of the Fraunhofer line produced by our model is in general agreement with the observations.’
- ‘Heights of formation of several Fraunhofer lines are indicated.’
- ‘Using this information, the two scientists identified what elements in the sun's atmosphere were causing Fraunhofer lines.’
- ‘In 1854 Stokes theorised an explanation of the Fraunhofer lines in the solar spectrum.’
- ‘By observing any star's Fraunhofer lines, an astronomer can identify the elements in that star's atmosphere.’
- ‘When they checked them against the Fraunhofer lines in the Sun they found everyone in precisely the right position.’
- ‘The roots of absorption spectroscopy can be traced to 1802, when the English chemist William Hyde Wollaston observed what later became known as the Fraunhofer lines - the many dark lines seen in the spectrum of sunlight.’
- ‘In 1864, Sir William Huggins matched some of the dark Fraunhofer lines in spectra from several stars with terrestrial substances, demonstrating that stars are made of the same earthly elements rather than exotic substances.’
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