Photoperiodism

Photoperiod is the length of daylight in a given day, which changes across the seasons because Earth's axial tilt alters the balance of daytime and nighttime hours as the planet orbits the sun, producing longer days in summer and shorter days in winter and opposite seasons in the Northern and Southern Hemispheres. Photoperiodism is the physiological response of an organism to that changing length of light and dark, occurring in both plants and animals. In plants it describes developmental responses to the relative lengths of light and dark, with species classified as short day, long day, or day neutral plants, while in animals, sometimes called seasonality, it describes the suite of physiological changes triggered by day length that let a species respond to a changing seasonal environment. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/