The reason is that darknessâor, to put it the other way, the absence of lightâstimulates the production of a hormone, melatonin, from its immediate precursor, the neurotransmitter serotonin. Like serotonin, melatonin plays important roles in our physical and mental well-being.
The five major ocean gyres. A gyre in oceanography is any large system of circulating ocean currents, particularly those involved with large wind movements. Gyres are caused by the Coriolis effect; planetary vorticity along with horizontal and vertical friction, determine the circulation patterns from the wind curl (torque).
Webster Dictionary(0.00 / 0 votes)Rate this definition: 1  Gyre(noun) a circular motion, or a circle described by a moving body; a turn or revolution; a circuit. 2  Gyre. to turn round; to gyrate.