Tides

In this picture, it is high tide. The water levels are at its highest point before shifting to low tide. Shifts from high tide to low tide occurs every six hours, therefore there are four tides per day (two high tides and two low tides).  These tides never occur at the same exact time each day. This is because the moon affects these tides. Tides are caused by the difference in force felt by opposite sides of the earth. The force between the earth and the moon is greater than the force between the sun and the earth because the moon is much closer. The moon takes 27 days to completely orbit around the earth. As a result the time of day and level of tides is constantly changing. There are spring tides that occur about two times a month. Spring tides are when the moon is directly in line with the sun and the earth. Spring tides have the highest high tides and the lowest low tides. The moon is full during spring tides.  There are also neap tides, which occur when the moon is directly above or below the earth. Neap tides are tides that don’t have the highest high or the lowest low.  The moon is halved during neap tides.