Miksi vuodenaikoja on neljä?
In temperate and subpolar regions, four calendar-based seasons are generally recognized: "spring", "summer", "autumn" or "fall", and "winter". The definition of seasons is also cultural. In India from the ancient times six seasons called Ritu are recognised and identified even today for the purposes such as agriculture and trade. Ecologists often use a six-season model for temperate climate regions which are not tied to any fixed calendar dates: "prevernal", "vernal", "estival", "serotinal", "autumnal", and "hibernal". Many tropical regions have two seasons: the "rainy", "wet", or "monsoon season" and the "dry season". Some have a third "cool", "mild", or "harmattan season". Seasons often held special significance for agrarian societies, whose lives revolved around planting and harvest times, and the change of seasons was often attended by ritual.
purposes such as agriculture and trade