Feature - Tidal Zone

Tidal Zone

The Tidal Zone is also known as the Littoral Zone and is the area of sea shore land that would be exposed when the tide falls to its lowest height.

In all text books and most web sites that explain the tides, you will be given a diagram of the Sun and Moon in relation to the Earth and shown the bulge of water that the two bodies create with their gravitation effect on our planets' ocean............ So we won't show you you that!

What we will show is the often overlooked perpective of just what it is that gives us a tidal influence on a daily basis.
If the Sun is considered, it is realised that the Earth takes a year to orbit it, so any varying effects it has will be on an annual basis, not daily.
If the Moon is considered, it is realised that it takes nearly four weeks to orbit the Earth, so any varying effects it has will be on a lunar month basis (springs and neaps), not daily.

In the UK, it is usual to get two rises and two falls in a daily twenty four hour period (although in some places this is different, due to such things as local land shapes effecting the movement of water)...... So what causes the daily cycle?

Daily Cycle

If the moon had no influence on the Earths' oceans, the gravitational effect would be even around the world and the tide height would remain much the same.
As it does have influence, the gravitational effect pulls at the oceans and gathers them to form the area of bulge (the area of high tide).

Imagine a point on land somewhere in the Equatorial region and fix a spot there in your mind. As that spot rotates to the right it will pass through a bulge, continue around the back (out of the bulge), appear again on the left and pass through the opposite bulge and continue across the front (again out of the bulge). Each time that point travels through a bulge it will be effected by higher levels of water (high tide) and each time the point travels between bulges it will be effected by lower levels of water (low tide).

Next time you are on the sea shore and it is high tide, it is because the point on the planet where you are standing, is passing through the bulge.
Next time you are on the sea shore and it is low tide, it is because the point on the planet where you are standing, has passed through and out of the bulge.......... but is heading towards the next one, so don't get cut off by the rising tide!