The possible hours of daylight in a given day is a function of the day of the year . In Poughkeepsie , New York , the minimum hours of daylight ( occurring on the Winter solstice ) is equal to 9 hours and the maximum hours of daylight ( occurring on the Summer solstice ) is equal to 15 hours If the hours of daylight can be modeled using a sinusoidal equation what is the equation's ampltitude ?