Vuorovesin

Vuorovesin, also known as tides, are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth. The gravitational pull of the Moon is the primary driver of tides, while the Sun's influence is about half as strong.

The Earth's oceans bulge outwards on the side facing the Moon due to its gravitational pull. On the opposite side of the Earth, a similar bulge occurs due to inertia and the centrifugal force created by the Earth's rotation. As the Earth spins, different locations on its surface pass through these bulges, experiencing high tide. In the areas between the bulges, the water level is lower, resulting in low tide.

Most coastal areas experience two high tides and two low tides each day, approximately every 12 hours and 25 minutes. This slight difference from a 12-hour cycle is because the Moon is also orbiting the Earth. The Sun's gravitational influence also plays a role, leading to variations in tidal range. When the Sun, Moon, and Earth are aligned (during new and full moons), their combined gravitational forces create larger tides known as spring tides. When the Sun and Moon are at right angles to each other relative to the Earth (during the first and third quarter moons), their gravitational forces partially cancel each other out, resulting in smaller tides called neap tides.

Tidal patterns can also be influenced by local factors such as the shape of the coastline, ocean depth, and the presence of bays or estuaries. These factors can modify the timing and amplitude of tides.