The relative length of day and night (or “photoperiod”) is the main factor that regulates the changes from one season to the next.

At the Biodôme, it is the natural light entering through the skylights and in particular the light from the artificial lighting system that determines the photoperiod.

In fall, the days become shorter until December 21, the shortest day of the year. Then they begin to lengthen, until we reach the longest day of the year, June 21.
Biodôme de Montréal

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