Calcolatore Durata del Giorno — Formula
## Daylight Duration
The number of hours between sunrise and sunset depends on latitude and the Sun's declination (which changes through the year).
### Formula
**D = (2/15) × arccos(-tan(φ) × tan(δ))** hours
where φ = latitude and δ = solar declination (both in degrees, converted to radians for calculation).
Solar declination ranges from -23.44° (Dec solstice) to +23.44° (Jun solstice).
The number of hours between sunrise and sunset depends on latitude and the Sun's declination (which changes through the year).
### Formula
**D = (2/15) × arccos(-tan(φ) × tan(δ))** hours
where φ = latitude and δ = solar declination (both in degrees, converted to radians for calculation).
Solar declination ranges from -23.44° (Dec solstice) to +23.44° (Jun solstice).
Esempio Risolto
New York (40.7°N) at summer solstice (declination = 23.44°).
- cos(H) = -tan(40.7°) × tan(23.44°)
- = -0.860 × 0.433 = -0.3726
- H = arccos(-0.3726) = 111.86°
- D = 2 × 111.86 / 15 = 14.91 hours of daylight