This is observed when the moon’s ray falls vertical on the equator every month.
Equinoctical spring Tides: Observed at an interval of every 6 anonths due to earth’s revolution around the sun.
Tropical Tides: Observed when moon’s rays fall vertically on the Tropic Cancer and Tropic of Capricorn. Such tides receive twice every month.
Daily Tides: Tides are observed at the intervals of 24 hours 52 minutes while the tides recurring at the intervals of 12 hours 26 minutes are semidiurnal tides.
Spring Tides: Very high tide is observed when the sun, the moon and the earth are almost in the straight and this arrangement is called syzygy.
The position of the sun and the moon in one side of the earth is called conjunction and this is possible during solar eclipse.
But when position of the sun, the earth and the moon are in right angle, this position is called quadrature. When the earth is present between the sun and moon then the position is called opposition.