Abstract
Observing and studying the solar radiation during solar eclipses is important in knowing the changes that occur to the environmental elements during this event. The main objective of this paper is the performance of the incoming variation of solar radiation components, global, direct and diffuse and their fractions during the partial annular solar eclipse on June 21st, 2020 in Helwan, Egypt (Lat. 29.866°N and Long. 31.20°E) has been made. A pyrheliometer for measuring the direct solar radiation, in three different bands; direct yellow (Y), direct red (R), direct infrared (IR), and also the total direct band (I); A pyranometers for measuring the different components of global solar radiation (G), global ultraviolet (GUV), global infrared (GIR) and a meteorological station to measure the different meteorological parameters. The duration of the solar eclipse was 01 h:59 m, and the maximum magnitude of the eclipse in this region was 0.449. The depression is clear at the solar radiation of all components due to the annular solar eclipse, while the depressions of the diffuse and global infrared solar radiation are lower. In all direct radiation compounds (I, Y, R and IR) are greatly affected by the eclipse. The diffuse fraction Kd is higher in the early time, before the partial eclipse, but during the partial annular eclipse time Kd values are suffers variation and through the day, where the values of Kd lies between Kt and KUV. The values of direct infrared solar radiation are dominant before and after the partial annular solar eclipse. The intensity of color bands (W∙m−2∙nm−1) are DIB3 > DIB2 > DIB4, and DIB1 is opposite direction with DIB3 and DIB2, the highest intensity is direct red and the lowest intensity is the direct infrared. The highest values of extinction coefficient in (GIR) solar radiation and the lowest values occur in (GUV) solar radiation, while the values of (G) solar radiation occur between them. In general trend, the values of extinction coefficient during the partial eclipse are increasing, while the minimum values of extinction coefficient occur at noon time due to the air mass is less value in the noon.
Highlights
A solar eclipse is a natural event that takes place on Earth when the Moon moves in its orbit between Earth and the Sun
The depression is clear at the solar radiation of all components due to the annular solar eclipse, while the depressions of the diffuse and global infrared solar radiation are lower
The diffuse fraction Kd is higher in the early time, before the partial eclipse, but during the partial annular eclipse time Kd values are suffers variation and through the day, where the values of Kd lies between Kt and KUV
Summary
A solar eclipse is a natural event that takes place on Earth when the Moon moves in its orbit between Earth and the Sun (this is known as an occultation). A total solar eclipse occurs when the Moon completely blocks the solar disk. In a total solar eclipse, the narrowest part of the path (where the Sun is completely blocked and the Moon casts its darkest shadow (called the umbra)) is called the “zone of totality”. When the Moon is farther away in its orbit than usual, it appears too small to completely cover the Sun’s disk. During such an event, a bright ring of sunlight shines around the Moon. A bright ring of sunlight shines around the Moon This type of eclipse is called an “annular” or “partial” eclipse. The partial solar eclipse was started at 06:23:09, the maximum eclipse will occur at 07:19:29 when the Sun reaches an altitude of 29.866 ̊ and azimuth of 078 ̊; this event will come to an end at 08:22:20 and will have a magnitude of 0.457 (the magnitude of an eclipse is the ratio of the apparent size of the Moon to the apparent size of the Sun during an eclipse), and an obscurity of 0.343 (the fraction of the Sun obscured)
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