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).
lyre. 1  a musical instrument of ancient Greece consisting of a soundbox made typically from a turtle shell, with two curved arms connected by a yoke from which strings are stretched to the body, used especially to accompany singing and recitation. ( 2 initial capital letter) Astronomy. the constellation Lyra.