Lined-up Sun, Moon give rise to `King tides`
High tides are extra high around the world when the Sun and the Moon align and are very near to the Earth, giving rise to the phenomenon, experts say.
New York: High tides are extra high around the world when the Sun and the Moon align and are very near to the Earth, giving rise to the phenomenon, experts say.
Meteorologist Dan Satterfield reported on his blog hosted by the American Geophysical Union that `King tides` happen when the gravitational forces of the Sun, Earth and Moon are aligned.
Tides are caused by the pull of the Moon and the Sun on masses of water.
Combined with the peculiarities of different coastlines, they result in differing local sea levels around the world.
According to Satterfield, this combined force is asserted when the Earth is at perihelion, the point in its orbit at which it is closest to the Sun and when the Moon reaches its perigee, the point during the month when it is closet to our planet.
"King tides" is a non-scientific term to describe these exceptionally high tides, which occur twice per year. These higher-than-usual tides can cause flooding if storms arrive when water levels are elevated, as happened in California in 2011.
A group of concerned citizens formed the `King Tides` Initiative in 2009, in which people worldwide were invited to take photos of local water levels during these high tides and to share them online.
One such initiative is sponsored by the Maryland Department of Natural Resources.