Classes starting with S
(cycle) Firstly: event(s) occurring every 14.76 days, the syzygic interval between extreme positions of the synodic cycle (full and new moon), also reflected in amplitude of semi diurnal tides (spring/neap tide cycle). Secondly, as intervals of 13.66 days, when the moon crosses the equator, twice a sidereal month, effecting diurnal tides.
(month) Or tropical month: cycle of moon around the earth relative to a distant star in 27.32 days.
(day/night) Phase of the free running rhythm in constant conditions, corresponding to day (night) time in light-dark conditions.
State in which two or more oscillations have the same frequency due to mutual or unilateral influences (referring both to ìentrainmentî and to ìmaskingî).
(month) Cycle of moon-phases resulting from orbital positions of earth, moon and sun, each 29.53 days.