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Four Light Seasons
The Light Calendar divides the year into four light-based seasons, defined by the Sun’s apparent ecliptic longitude.
The structure is anchored at PH0 = 315°, which marks the beginning of the Light Year. From this reference, all seasonal boundaries are derived from fixed solar angles rather than time-based midpoints.
Each Light Season represents a distinct mode of daylight behaviour within the annual light curve. Together, they form a continuous progression in which the rate and stability of day-length change vary predictably over the year.
For finer resolution, two of the seasons are subdivided into internal phases, reflecting gradual transitions in light dynamics.
Lighttime data is evaluated only for latitudes |φ| ≥ 18°, where seasonal variation in day length is perceptible.
Approx. 4 February – 4 May
PH0 = 315°
Waxing Light begins at PH0 (≈ 315° solar longitude), shortly after the annual light minimum. Daylight increases rapidly, and the annual light curve shows its steepest upward slope. This season marks the most dynamic phase of light growth.
Approx. 5 May – 6 August
PH1 = 45°
Light Time spans the region of high and sustained daylight around the annual light maximum. While total daylight remains high throughout, the rate of change varies across three internal phases defined by solar longitude.
2a. Arrival in Light (Ankommen im Licht)
Approx. 5 May – 20 May
PH1 = 45°
The transition into consistently long days. Daylight growth slows as the solar maximum approaches.
2b. Light Rest (Lichtruhe)
Approx. 21 May – 22 July
PH2 = 60°
The central high-light region. Day-to-day changes in daylight are minimal, forming a broad light plateau.
2c. Departure from Light (Abschied vom Licht)
Approx. 23 July – 6 August
PH3 = 120°
Daylight remains dominant, but decline becomes perceptible as the annual curve begins to turn downward.
Approx. 7 August – 7 November
PH4 = 135°
Waning Light mirrors Waxing Light in reverse. Daylight decreases rapidly, and the annual light curve shows a steep downward slope. The seasonal dynamic is symmetrical, but inverted.
Approx. 8 November – 3 February
PH5 = 225°
Dark Time surrounds the annual light minimum and represents the period of minimal daylight. As with Light Time, it contains a central region of relative stability framed by transitional phases.
4a. Arrival in Darkness (Ankommen im Dunkeln)
Approx. 8 November – 21 November
PH5 = 225°
The rate of daylight loss slows as the dark minimum approaches.
4b. Dark Rest (Dunkelruhe)
Approx. 22 November – 19 January
PH6 = 240°
The central low-light region. Daylight length changes very little, forming a dark valley.
4c. Departure from Darkness (Abschied vom Dunkeln)
Approx. 20 January – 3 February
PH7 = 300°
The first perceptible return of light; the annual curve begins to rise again toward PH0.
Total length: 365 days.
Small ±1-day variations occur when fixed solar-angle boundaries are mapped onto the Gregorian calendar.
The structure of the Light Calendar is identical in the Southern Hemisphere. Only the seasonal assignment shifts by half a year; durations, angular relationships, and internal structure remain unchanged.