- Education and Science»
- Geography, Nature & Weather
How Tides Form
Tides is the regular rise and fall of the water levels in the Earth's seas and oceans. The reason why this occurs is because of the gravitational effect of the Sun and Moon. As a matter of fact, the Moon exerts a much stronger pull than the Sun, around twice the effect, and the variation in tides is caused by the relative positions or angles of the three bodies (Earth, Moon and Sun) and the distribution of water on the Earth.
When the Sun, Moon and Earth are aligned, the effects are combined and result in a maximum, the high 'spring tide', and this is when the Moon is new or full. When the Sun is at right angles to the Moon, the combination of the effects is minimized resulting in a low 'Neap tide'. (Refer to the diagrams for clearer and further understanding)
High Tide in Porthleven Pier in Cornwall
The effect of tides in the open oceans is rather unimportant or negligible, perhaps one meter, and enclosed areas of water such as the Black Sea for example, exhibit differences in the order of centimeters. However, in shallow waters (or seas) where the tide may be channeled by the shores, tides of 5 to 10 meters may be created.
The tides around Britain's coasts for example, vary noticeably and clearly due in part to the effect of the Coriolis effect (also can be called the Coriolis force). This effect is when air or water is pushed to the side because of the rotation of the Earth. Hence in the northern hemisphere, water moving across the surface is pushed to the right, and vice-versa in the southern hemisphere. Hence the tidal wave which passes northwards up the Irish Sea in Europe creates higher tides on the Welsh and English coasts than on the Irish side, and as the tidal wave moves into the North Sea, the Coriolis effect pushes the water to the right giving higher tides on the coastline of Britain than on the coasts of Denmark and Norway. The potential for generating energy from tides has long been realized and the first tidal power station was built in France 26th November 1966 and known as the Rance Tidal Power Plant.