There is a Talmudic statement that there are six seasons in the year. This ritual for the sixth night of Chanukah honors the six seasons and reimagines Chanukah as a rededication of the earth. While it is common to think of there being four seasons, according to Gen. 9:22 the seasons' number six. When Noah emerges from the ark, the Creator makes a covenant with Noah and all of creation by means of a rainbow, saying: "As long as the days of the earth endure, seedtime and harvest, cold and heat, summer and winter, and day and night, shall not cease." We also see the number six in the six visible colors of the rainbow. Six is the balance and beauty of the physical world.
Special appreciation to Tel Shemesh which is a web resource.