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The angle of incidence at which light is first totally internally reflected is known as the critical angle. The angle of reflection and angle of refraction are other angles related to beams. In computer graphics and geography , the angle of incidence is also known as the illumination angle of a surface with a light source, such as the Earth 's ...
The timeline of the COVID-19 pandemic lists the articles containing the chronology and epidemiology of SARS-CoV-2, [1] the virus that causes the coronavirus disease 2019 and is responsible for the COVID-19 pandemic. The first human cases of COVID-19 occurred in Wuhan, People's Republic of China, on or about 17 November 2019. [2]
The human coronavirus NL63 shared a common ancestor with a bat coronavirus (ARCoV.2) between 1190 and 1449 CE. [76] The human coronavirus 229E shared a common ancestor with a bat coronavirus (GhanaGrp1 Bt CoV) between 1686 and 1800 CE. [77] More recently, alpaca coronavirus and human coronavirus 229E diverged sometime before 1960. [78]
The history of coronaviruses is an account of the discovery of the diseases caused by coronaviruses and the diseases they cause. It starts with the first report of a new type of upper-respiratory tract disease among chickens in the U.S. state of North Dakota, in 1931.
Atmospheric refraction of the light from a star is zero in the zenith, less than 1′ (one arc-minute) at 45° apparent altitude, and still only 5.3′ at 10° altitude; it quickly increases as altitude decreases, reaching 9.9′ at 5° altitude, 18.4′ at 2° altitude, and 35.4′ at the horizon; [4] all values are for 10 °C and 1013.25 hPa ...
In part correct, [2] being able to successfully explain refraction, reflection, rectilinear propagation and to a lesser extent diffraction, the theory would fall out of favor in the early nineteenth century, as the wave theory of light amassed new experimental evidence. [3] The modern understanding of light is the concept of wave-particle duality.
The government launched several initiatives to address these shortages, including converting public buildings into COVID-19 care centers and increasing domestic production of medical supplies. Unfortunately, the second wave of COVID-19 hit India in April 2021, resulting in even higher numbers of cases and deaths than the first wave.
This article documents the chronology and epidemiology of SARS-CoV-2 in 2019, the virus that causes coronavirus disease 2019 and is responsible for the COVID-19 pandemic. The first human cases of COVID-19 known to have been identified were in Wuhan, Hubei, China, in December 2019.