Found this really amazing and relaxing for a end of the day. Enjoy.
The Severn Bore is one of Britain's few truly spectacular natural phenomena. It is a large surge wave that can be seen in the estuary of the River Severn, where the tidal range is the 2nd highest in the world, being as much as 50 feet (approx. 15.4m).
The typical tidal range in the open ocean is about 0.6 meters (2 feet).
Tidal range: it is the difference in height between high and low water and will vary throughout the tidal cycle. The most extreme tidal range will occur around the time of the full or new moons, when gravitational forces of both the Sun and Moon are in phase and acting in the the same direction (new moon), or exactly opposite way (full).
The largest annual tidal range can be expected around the time of the Equinox(that occurs twice a year), if coincidental with a spring tide.
The shape of the Severn estuary is such that the water is funnelled into an increasingly narrow channel as the tide rises, thus forming the large wave.
As well as the width of the river decreasing rapidly, then so does the depth of the river also change rapidly, thereby forming a funnel shape. Therefore as the incoming tide travels up the estuary, it is routed into an ever decreasing channel. Consequently the surge wave or bore is formed.
The Severn Bore is one of the biggest in the world but bores also occur on the Seine and Gironde in France, on the Indus, Hooghly and Brahmaputra in India, on the Amazon in Brazil, on the Petitcodiac, New Brunswick, and also the Knik Arm bore at the head of Cook Inlet, Alaska. By far the biggest bore in the World is the Ch'ient'ang'kian (Hang-chou-fe) in China. At spring tides the wave attains a height of up to 25 ft (7.5 m) and a speed of 13-15 knots (24-27 km/h). It is heard advancing at a range of 14 miles (22 km).
At the end you can see some guys trying to surfing it.
All credits go to pjenni12.
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