Tide clock This is often complicated because the lead or lag varies during the course of the lunar month, as the lunar and solar tides fall into and out of synchronization. The lunar tide and solar tide are synchronized (ebb and flow at the same time) near the full moon and the new moon. The two tides are unsynchronized near the first and last quarter moon (or "half moon"). Also, in addition to the relative position of the moon and the elliptical pattern of the sun, the tide can be affected to some degree by wind and atmospheric pressure. All of these
Full moon the sun. To compare, in 1983 the equal length seasons began at 1.48 AM on 23 March, 9.15 AM on 22 June, 4.42 PM on 21 September and 12.10 AM on 22 December, while the astronomical seasons began at 4.39 AM on 21 March, 11.09 PM on 21 June, 2.42 PM on 23 September and 10.30 AM on 22 December (all times GMT). Due to a misinterpretation of this definition in the March 1946 "Sky & Telescope" magazine, "blue moon" has also been used in the sense of "the second full moon in any month which contains two full moons