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 boundary current of the North Atlantic Gyre is the Gulf Stream, of the North Pacific Gyre the Kuroshio Current, of the South Atlantic Gyre the Brazil Current, of the South Pacific Gyre the East Australian Current, and of the Indian Ocean Gyre the Agulhas Current. Subpolar gyres. Subpolar gyres form at high latitudes (around 60Â°).