Tides and stuff

Cassie Brown~Oct. 28~Marine Biology

How do Tides Work?

Tides are formed from gravitational pull between the spinning earth and the moon and the sun every 12 hours. The moon pulls the water from the ocean towards it, and inertia causes the water on the opposite side to rise away from the earth as well. As the earth spins, the water bulges in different places, causing high tides. Tides are semidiurnal, which means we have 2 high tides and 2 low tides a day as the earth rotates. But because of the moon's rotation around the earth, oceans that are more northern or more southern are diurnal with only one low tide and one high tide a day.

Special Tides

The sun also has some effect on the tides, and during a half moon, the sun lessens the moon's effect on the tides, which causes a low high tide and a high low tide, or a neap tide. However, during new moons, the sun pulls the water further from the earth, causing high high tide and low low tides, or spring tides.


Contrary to popular belief, tides don't occur every 24 hours. Tide schedules actually last 24 hours and 50 minutes, making every tide occur 50 minutes later than the day before. Tides also occur not only in oceans but in any bodies of water affected by gravity.