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 curvature of the winds created by the Coriolis effect also helps create surface ocean currents. The wind drags on the water's surface, creating spiral currents called gyres. As you may have guessed, the gyres in the Northern Hemisphere spin clockwise and the ones in the Southern Hemisphere spin counterclockwise.