The change in the sun's diurnal orbit on the celestial sphere causes the transitions of seasons. In winter, because of the lower altitude of the sun, hours of sunlight decrease substantially and ambient temperatures descend sharply.
In the autumnal garden dressed with various flaming colors, living things have sensed the subtle signs of the coming winter and quietly begun to prepare for the cold and harsh season.
Soon deciduous trees shed all of their colored leaves in haste to defend themselves against the severe coldness and insufficient sunshine of midwinter. Before long, they will enter into quiet winter sleep and dream of the warm spring sunlight.