Tidal range Tidal range Tidal range is the height difference between high tide and low tide. Tides are the rise and fall of sea levels caused by gravitational forces exerted by the Moon and Sun and the rotation of Earth. Tidal range is not constant but changes depending on the locations of the Moon and Sun. The most extreme tidal range occurs during spring tides, when the gravitational forces of both the Moon and Sun are aligned (syzygy), reinforcing each other in the same direction (new moon) or in opposite directions (full moon). During neap tides, when the Moon and Sun's gravitational
Chinese sun and moon mirrors "fangzhu" mirrors "jiàn" 見 "seeing" the sun and moon. The Way of Heaven is called the Round; the Way of Earth is called the Square. The square governs the obscure; the circular governs the bright. The bright emits "qi", and for this reason fire is the external brilliance of the sun. The obscure sucks in "qi", and for this reason water is the internal luminosity of the moon. Emitted "qi" endows; retained "qi" transforms. Thus yang endows and yin transforms. The unbalanced "qi" of Heaven and Earth, becoming perturbed, causes wind; the harmonious "qi" of Heaven and Earth, becoming calm,