Visitors to the seaside resort of De Haan had a rather unusual experience yesterday during the half-term break when a waterspout appeared off the coast. A waterspout is a tornado occurring over water that forms a column of water and mist extending between the surface and the clouds above. "To get this you need wind shear, when the direction of the wind or the wind speed changes rapidly at height," explains weatherman Bram Verbruggen.
It was a striking sight off the coast of De Haan Tuesday. The waterspout suddenly descended from a thundery cloud to the surface of the North Sea. Passers-by were able to film and photograph this exceptional phenomenon.
"A waterspout is a whirlind over the sea," explains weatherman Bram Verbruggen. "Two factors are needed. On the one hand, you need a thundery cloud, like the one hanging over the North Sea yesterday. On the other, you require wind shear, when the wind direction or wind speed changes rapidly at height."
"In such a thundery cloud there are upward and downward forces. Combined with the wind shear, the downward forces can start to rotate. This is how they form a waterspout. It can float loose in the air, but sometimes it hits the surface of the sea."
"The water in a waterspout like this largely comes from a thundery cloud. On contact with the surface of the sea, some water may also be sucked up. A waterspout usually lasts a few seconds to a few minutes. Only in extreme cases do they last longer."
"They are not really dangerous, the trunk is usually only a few metres wide. Still, I wouldn't want to be at the bottom of one in a small sailing boat. Above land, whirlwinds do pose a greater risk, especially if they grow into real tornadoes."