Types of Tides
The periodical rise and fall of the sea level, once or twice a day, mainly due to the attraction of the sun and the moon, is called a tide. Tides vary in their frequency, direction, and movement from place to place and also from time to time. Tides may be grouped into various types based on their frequency of occurrence in one day or 24 hours or based on their height.
Tides based on Frequency
Semi-diurnal tide: The most common tidal pattern, featuring two high tides and two low tides each day. The successive high or low tides are approximate of the same height.
Diurnal tide: There is only one high tide and one low tide during each day. The successive high and low tides are approximate of the same height.
Mixed tide: Tides having variations in height are known as mixed tides. These tides generally occur along the west coast of North America and on many islands of the Pacific Ocean.
Tides based on the Sun, Moon, and the Earth Positions
The height of rising water (high tide) varies appreciably depending upon the position of sun and moon with respect to earth. Spring tides and neap tides come under this category.