Why are there different tidal ranges in different parts of the world?
Every body of water of any size has a natural frequency of oscillation. The tide-raising forces which act upon the surface of the earth will produce an imposed-force on that body of water. If the frequency of the imposed force is the same as the natural frequency, resonance will occur and very large movements of water (or displacements) will occur from very small applied forces. The natural period of oscillation is the decisive factor in determining whether the water mass responds by one of three regimes, namely diurnal (one High and One Low Water per lunar day), semi-diurnal (two High and Low Waters per lunar day) or mixed (features of both, where the diurnal inequality is relatively large). Where the oceanic tide enters the shallow water on the continental margins, the tidal range is amplified accordingly. Depending on the shape of the bordering land masses, this can further compound the tidal wave, constricting and funnelling it in sympathy with its natural resonance, creating huge
