Tidal patterns found in the ocean
Tides are periodic rise and fall of the sea surface due to the attraction of the sun & moon their effect is noticeable in costal oceans. Tides are due to the forces of:
Gravitational attraction of sun on the earth
Gravitational attraction of moon on the earth
Centrifugal force generated by rotating earth.
There are 2 type of tides:
1. Daily tides
2. Monthly tides
1. Daily tides: diurnal tide, semi diurnal tide, mixed tide.
Diurnal tides: this having only one high tide and low tide each day. These are called diurnal tides.
Semi diurnal tides: some tides have 2 high tides & 2 low tides & they have approximately equal heights .eg : Sri lankan costal tides .
Mixed tides: these have 2 high tides & 2 low tides but these 2 high tides are different in heights and the same is true for 2 lows.
2. Monthly tides:
1. Spring tide
2. Neap tide
Spring tides: these occur during full and new moon days. At this time earth , moon and sun are in a same line the gravitational forces of moon & sun are in the same direction when spring tides are produced. Higher high tide & lower low tide leads to highest tidal fluctuation.
Neap tides: when sun’s & moons gravitational forces are not in the same line neap tides occur . High tide is lowest & low tide is highest leading to a lowest fluctuation.