Photoperiod Calculator

Computation of Daylengths, Sunrise/Sunset Times, Twilight and Local Noon

Select for dates Use the current date Input a date value	Select for locations Use menu of cities Input latitude/longitude	Daylight savings Set ON/OFF
Calculation Date Year	Month	Day
Location
Latitude	° ´	N S Find latitudes
Longitude	° ´	W E Find longitudes
Local time	h. min. TZ	Find Time Zones
Temperature	^oC	Refraction

Morning: - Begin of Nautical (= End of Astronomical) Twilight: Sun is 12 degrees below horizon - Begin of Civil (= End of Nautical) Twilight: Sun is 6 degrees below horizon - Sunrise: Sun is 0.83 degrees (= 50 arc-minutes) below horizon Noon: Sun is at meridian, max. altitude Evening: - Sunset: Sun is 0.83 degrees (= 50 arc-minutes) below horizon - End of Civil (= Begin of Nautical) Twilight: Sun is 6 degrees below horizon - End of Nautical (= Begin of Astronomical) Twilight: Sun is 12 degrees below horizon Solar radiation max power at noon, calculation for a constant extinction coefficient 0.9 assumed Solar azimuth: direction angle clockwise, north = zero, south = 180