How fast the days are getting longer (2023)

Experiencing Latitude: From Tropics to Arctic

• Many comments contrast life near or above 60°N with mid‑latitudes and tropics.
• High latitudes: people describe “zigzag” seasonal light as life‑defining—months of near‑constant day or night, rapid changes around equinoxes, and strong effects on mood, sleep, and daily rhythm.
• Tropics: sunrise/sunset are abrupt and near‑constant in time and length; seasonal change is minimal, which some find comforting and “normal.”
• Several describe moving between these regimes (e.g., Brazil→Sweden, Orlando→Seattle, Seattle→Central America) and being surprised how strongly daylength, not just temperature, shapes their life.

Twilight, Refraction, and What Counts as ‘Day’

• Multiple posts note that simple “daylength” calculations understate usable light at high latitudes because of twilight and atmospheric refraction.
• Civil, nautical, and astronomical twilight are discussed; at ~60°N midsummer, it never becomes fully dark, even if “night” is a few hours on paper.
• Some wish for a follow‑up focused just on twilight duration as a function of latitude and season.

Math, Graphs, and Extremes

• Readers discuss how daylength vs. time deviates from a pure sine wave, especially near the Arctic Circle where curves look almost like triangle or square waves and produce singularities in the rate of change.
• There’s debate over whether the “zigzag” near the Arctic Circle is exactly straight (it isn’t; it’s just a good approximation).
• Questions arise about correctness at extreme latitudes and the need for corrections like refraction and the analemma for precise solar positions.

Equator, Time Perception, and Seasons

• Some are surprised by the near‑12‑hour day at the equator; others from equatorial regions find mid‑latitude seasonality mind‑blowing.
• Clarification: equatorial daylength is “exactly 12 hours” only to hour‑level approximation; refraction adds minutes.
• People discuss how equatorial climates often lack familiar four‑season patterns, reshaping concepts like “winter” and “evening.”

Daylight Saving Time and Time Zones

• Strong dislike of DST, especially at high latitudes where rapid natural change makes the one‑hour shift feel pointless or harmful.
• Some note economic/time‑zone coordination as the only real justification.
• Time zone boundaries also distort perceived sunrise/sunset, sometimes canceling DST’s intended effect locally.

Health, Mood, Religion, and Daily Routines

• Many tie daylight patterns to seasonal affective disorder, productivity, and preferred schedules (e.g., alarms keyed to civil twilight).
• Several describe religious practices (Ramadan fasting, Sabbath timing) that make changing daylength very salient, especially as lunar calendars drift through the solar year and across extreme latitudes.