Daglengd

Daglängd is a geographic and meteorological term describing the length of the daily daylight period at a specific location and date. It is defined as the interval between sunrise and sunset, expressed in hours and minutes, and is affected by the observer’s solar definition—civil, nautical, or astronomical—and by atmospheric refraction, which can add several minutes to the measured value.

The term Daglengd derives from dag meaning day and lengd meaning length in several Germanic languages, and it is used in Nordic and Baltic scientific and cultural contexts.

Daglängd varies with latitude and season. Near the equator, day length remains close to 12 hours year-round, while at higher latitudes it lengthens toward the summer solstice and shortens toward the winter solstice. At extreme latitudes, daylight can approach 24 hours for extended periods during the summer (polar day) and drop to 0 hours during the winter (polar night).

Practically, daglengd informs agriculture, energy planning, and tourism, and it is used in climate research to model seasonal cycles. In literature and folklore, it is sometimes invoked as a symbol of time, mood, or the rhythm of life in northern communities.