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The tides whose height is 20 percent more than normal tide are called
Explanation
Spring tides occur when the Sun, Moon, and Earth align in a straight line (syzygy) during the new moon and full moon phases [1]. During this alignment, the gravitational forces of the Sun and Moon combine to reinforce each other, causing the oceans to bulge more than usual [2]. This results in tides of maximum height and depression, where high tides are significantly higher and low tides are lower than average. Specifically, spring tides are approximately 20% higher than normal tidal heights. In contrast, neap tides occur when the Sun and Moon are at right angles, causing their forces to counteract and produce lower-than-average tidal ranges [4]. While perigean tides (when the moon is at perigee) also result in unusually high tides, the specific 20% increase over normal tides is the standard characteristic attributed to the syzygy alignment of spring tides.
Sources
- [1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > Tides based on the Sun, Moon and the Earth Positions > p. 110
- [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > Neap Tides > p. 504
- [4] https://en.wikipedia.org/wiki/Perigean_spring_tide