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).
These major spirals of ocean-circling currents are called âgyresâ and occur north and south of the equator. They do not occur at the equator, where the Coriolis effect is not present (Ross, 1995). There are five major ocean-wide gyresâthe North Atlantic, South Atlantic, North Pacific, South Pacific, and Indian Ocean gyres.