Tides, Waves, and Ocean Movements - Class VIII

Neap tides occur when the sun and moon are at right angles relative to the earth, causing their gravitational forces to partially cancel each other out, resulting in lower high tides.

Tides are the periodic rise and fall of sea levels caused by the gravitational forces exerted by the moon and the sun, and the rotation of the earth.

Spring tides occur when the earth, moon, and sun are aligned, causing their gravitational forces to combine and produce higher high tides and lower low tides.

Neap tides occur during the first and third quarters of the moon phase, when the sun and moon are at right angles to the earth.

The variation between spring and neap tides is evidence that both the sun and the moon exert gravitational influence on the earth's oceans.

While the sun also exerts a gravitational pull, the moon is the primary driver of tides due to its proximity to the earth.

Ripples are the instant effect of wind on water and they die down as quickly as they form, as the surface tension of the water dampens their efforts.

Waves always travel in the same direction as the wind is blowing: if the wind changes then the waves change with it. Wave size is determined by the strength of the wind, the length of time it has been blowing and the distance it has blown over or the ‘fetch’.

When strong winds blow for longer than a few hours, it gives the water sufficient energy that it then takes on a character of its own. This character and movement is known as swell, and it will march across open areas of water independent of the wind.

Wind blowing over the surface of the ocean creates friction, which transfers energy to the water and generates waves.