A formula for the number of days between the winter solstice and the latest sunrise

摘要

A simple closed-form expression for the number of days between the wintersolstice and the latest sunrise is derived. Formulas for the summer solsticeand the sunset are derived as well. These approximate formulas make it easy tosee the functional dependence on the latitude of the observer. An approximateexpression for the difference in time of day between the latest sunrise and thesunrise on the solstice is also derived. The formulas are not valid in theArctic, Antarctic or tropics.