semi-diurnal tide

A semi-diurnal tide occurs when the ocean experiences two high tides and two low tides roughly every 24 hours and 50 minutes. This pattern happens because the moon’s gravitational pull creates two bulges of water on opposite sides of the Earth—one facing the moon and one opposite. As Earth rotates, these bulges pass under different locations, leading to two high tides per day. The effect is consistent and predictable, influenced by the relative positions of the moon, sun, and Earth, resulting in a regular cycle of high and low tides every approximately 12 hours and 25 minutes.