Amphidromic point
![The M2 tidal constituent, the amplitude indicated by color. The white lines are cotidal lines spaced at phase intervals of 30° (a bit over 1 hr).[4] The amphidromic points are the dark blue areas where the lines come together.](/Images/godic/202412/20/M2_tidal_constituent2027.jpg")
![Amphidromic system of the M2 constituent in the North Sea. The light-blue lines are lines of equal tidal phase for the vertical tide (surface elevation) along such a line, and the amphidromic points are denoted by 1, 2 and 3.](/Images/godic/202412/20/Amfidromieen2028.JPG")
An amphidromic point is a point of zero amplitude of one harmonic constituent of the tide. The tidal range (the amplitude, or height difference between high tide and low tide) for that harmonic constituent increases with distance from this point. These points are sometimes called tidal nodes.