Why are there two high tides and two low tides in a day?
The moon exerts a gravitational pull on earth. As a result, the ocean and Earth itself is pulled towards the moon. Confusingly, this means that the ocean bulges at the side closest to the moon as well as on the side furthest from the moon. As the Earth spins underneath the moon (one full spin for every 24 hours) so the swelled oceans move along the surface of Earth to stay positioned below the moon. As a result, the tides are high twice a day and low twice a day.
