White-light solar corona structure observed by naked eye and processed images

Abstract

Light and dark adaptation and luminance contrast enhancement are well-known characteristics of human vision that allow us to observe a wide range of light intensity not fully captured in standard camera images. The naked-eye observations of total eclipses, some recorded with spectacular detail in artists’ paintings, reveal structure that is consistent with images obtained by telescopes equipped with recording media. The actual shape of the corona during a total eclipse depends not only on the phase of the solar cycle but, as can be simply demonstrated, also on the day-to-day variability and spatial distribution of coronal intensity that is determined by solar surface magnetic fields, including the locations of coronal holes that are the sources of high-speed solar wind causing geomagnetic storms. The latter were very similar for the eclipses in 1932, 1994, and 2017, which is the main reason why the naked-eye observations, as well as the processed images (1994 and 2017), of the white-light corona displayed very similar shapes. White-light corona image processing is a useful technique to enhance the contrast to observe fine-scale structure that is consistent with the physics of the solar atmosphere shaped by the magnetic field drawn out into the interplanetary space by solar wind.

Heavy rainfall, floods, and flash floods influenced by high-speed solar wind coupling to the magnetosphere–ionosphere–atmosphere system

“…Measurements of the green coronal emission line (Fe XIV; 530.3 nm) by ground-based coronagraphs from 1939 to 2008 have been merged into a homogeneous coronal data set (Rybanský, 1975;Rybanský et al, 2001Rybanský et al, , 2005 https: //ngdc.noaa.gov/stp/solar/solar-indices.html, last access: 11 August 2021). The intensity of the emission line at 28.4 nm (Fe XV) observed by the SOHO Extreme ultraviolet Imaging Telescope (EIT) instrument was found to be closely correlated with intensity of the green corona obtained by ground-based coronagraphs (Dorotovič et al, 2014).…”

Heavy rainfall, floods, and flash floods in the context of solar wind coupling to the magnetosphere-ionosphere-atmosphere system

“…Measurements of the green coronal emission line (Fe XIV; 530.3 nm) by ground-based coronagraphs from 1939 to 2008 have been merged into a homogeneous coronal data set (Rybanský, 1975;Rybanský et al, 2001Rybanský et al, , 2005 https: //ngdc.noaa.gov/stp/solar/solar-indices.html, last access: 11 August 2021). The intensity of the emission line at 28.4 nm (Fe XV) observed by the SOHO Extreme ultraviolet Imaging Telescope (EIT) instrument was found to be closely correlated with intensity of the green corona obtained by ground-based coronagraphs (Dorotovič et al, 2014).…”