Why it’s so dark in the morning
JAN 15, 2013
DOI: 10.1063/PT.5.026686
New York Times : It is common knowledge that the days are shorter in the winter and longer in the summer. Yet, for those of us in the Northern Hemisphere, January mornings seem to be particularly dark. The reason is complex and has to do with the fact that actual days are not exactly 24 hours long. And because Earth’s axis is tilted, its orbit elliptical, and its orbiting speed variable, sunrise and sunset times are not symmetrical. Hence, the difference between the time measured by a sundial and that measured by a clockâmdash;as calculated by the equation of time âmdash;can vary by as much as 16 minutes. In his New York Times article, John O’Neil discusses the complexities involved, including why sunrise stayed at 7:20am from 28 December until 11 January, while sunset got pushed later daily.
© 2013 American Institute of Physics
