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).
Ocean Gyres. The major gyres of the ocean include: North Atlantic, South Atlantic, North Pacific, South Pacific and Indian Ocean gyres. A simplistic drawing of those can be seen on this page. Many other smaller gyres exist in the ocean too. One such smaller gyre is the Beaufort gyre found in the Arctic Ocean. The Beaufort gyre is a huge vortex of water being driven by strong winds that force currents in a clockwise direction. This gyre is full of relatively fresh water as Siberian and Canadian rivers drain into the Beaufort gyre.