Solar eclipses have an impact on twilight, primarily on sky brightness as scientists from the Hoher-List Observatory, Rhineland, Germany during the eclipse of solar eclipse of July 22, 1990 measured the brightness. Their results showed "a deep minimum in twilight during the main phase of the solar eclipse compared with normal conditions." This was reduced by 83%.
Causes Using a first order scattering model, the sky radiation 100-200 km away from the umbra depends on the height profile of the air pressure.
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