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).
The following are the five most notable gyres: 1  Indian Ocean Gyre (generally flowing counter-clockwise) 2  North Atlantic Gyre. 3  North Pacific Gyre. 4  South Atlantic Gyre. 5  South Pacific Gyre.