why is a tidal cycle 25 hours?

Question

why is it 25 hours and NOT 24 hours??

Answer 1

Victoria - the earth's tidal cycle is not based on the length of the earth day but rather on the lunar day.

Tides are the cyclic rising and falling of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans. Tides cause changes in the depth of the marine and estuarine water bodies and produce oscillating currents known as tidal streams.

The changing tide produced at a given location is the result of the changing positions of the Moon and Sun relative to the Earth coupled with the effects of Earth rotation and the local bathymetry.

The various frequencies of astronomical forcing which contribute to tidal variations are called constituents. In most locations, the largest is the "principal lunar semidiurnal" constituent, also known as the M2 (or M2) tidal constituent. Its period is about 12 hours and 24 minutes, exactly half a tidal lunar day, the average time separating one lunar zenith from the next, and thus the time required for the Earth to rotate once relative to the Moon.

Answer 2

Tides, as you probably know, are caused (mainly) by the moon. As the earth rotates, it takes about 25 hours for the moon to reach roughly the same spot in the sky. The reason it doesn't take 24 hours, is that the moon is moving in its orbit during that time. So every day, the moon is about an hour "behind" where it was the day before.

For the same reason, the times of moonrise and moonset are roughly an hour later every day.

Answer 3

Because the tides are primarily caused by the gravitation of the moon. And the moon does not stand still while the Earth rotates under it.