EducationgeologySciences

Tides.

What is a tidal wave?

A tidal wave is a shallow water wave caused by the gravitational interactions of the sun, moon and earth on the ocean.

The rise and fall of tides play an important role in the natural world and can have a noticeable effect on marine-related activities.

Tides are basically long, slow waves caused by the gravitational pull of the moon and, to a lesser degree, the sun at the surface of the earth. Because the moon is much closer to the earth than the sun, its clouds have a greater effect on the tides.

The moon’s gravity forces the ocean to bulge outward on either side of the Earth, causing the water level to rise in the places aligned with the moon and the water level to drop midway between the two places. This rise in water level is accompanied by a horizontal movement of water called a tidal current.

_ How do tides and waves work?

Understanding ocean waves is an important part of understanding the coastal habitats that affect them.

In general, there are three types of ocean waves:

(Wind-driven waves, tidal waves, and tsunamis).

1. Wind-driven waves.

They are waves that form when winds pass over the surface of open water. Energy is transferred from wind to the upper layers of water by means of friction and pressure.

These forces cause turbulence that travels through sea water. It should be noted that it is the wave that moves, not the water itself (mostly).In addition, the behavior of waves in the water adheres to the same principles that govern the behavior of other waves such as sound waves in the air.

2. Tidal waves.

It is the largest ocean wave on our planet. Tidal waves are formed by the gravitational forces of the earth, the sun and the moon.

The gravitational forces of the sun and the moon (to a greater extent) pull in the oceans, causing the oceans to swell on both sides of the Earth (the side closest to the moon and the side farthest from the moon). When the Earth rotates, the tides flow “ in ” and “ out ” (the earth is moving but the water bulge remains in line with the moon, giving the appearance that the tides are moving when the Earth is, in fact, in motion).

3. Tsunami.

They are large and strong ocean waves resulting from geological disturbances (earthquakes, landslides, and volcanic eruptions) and are usually very large waves.

How waves behave when encountering other waves.

Superposition.

When waves pass through the same medium simultaneously through each other, they do not disturb each other. At any point in space or time, the net displacement observed in the medium (in the case of ocean waves, the medium being seawater) is the sum of the displacements of the individual wave.

Destructive interference.

Destructive interference occurs when two waves collide and the crest of one wave coincides with the trough of another wave. The result is that the waves cancel each other out.

Structural overlap.

Constructive interference occurs when two waves collide and the crest of one wave coincides with the crest of another. The result is that the waves add to each other.

Where earth meets sea.

When the waves meet the shore, they are reversing which means that the wave is being pushed back or resisted by the shore (or any solid surface) so that the wave’s motion is returned in the other direction.

Plus, when the waves meet on the shore, they break. As the wave approaches the shore, it experiences friction as it moves over the sea floor. This force of friction acts to bend (or refract) the wave differently depending on the characteristics of the sea floor.

How ocean currents work.

Although tidal currents do not have much effect in the open ocean, they can create a fast current of up to 15.5 miles (25 kilometers) per hour when it flows in and out of narrow areas such as bays, estuaries and harbors.

Rapid tidal currents blow off sediments and affect plant and animal life. The currents may, for example, carry fish eggs from an estuary to the open sea or carry nutrients that fish need from the sea to the downstream.

The strongest tidal currents occur at or around the height of the high and low tides. When the tide rises and the flow of the current is directed towards the shore, the tidal current is called the flood current, and when the tide recedes and the current is directed back to the sea, it is called the tidal current.

Because the relative positions of the Moon, the Sun, and the Earth change at a known rate, the tidal currents are predictable.

Currents, whether tidal, surface or deep ocean, profoundly affect theworld as we know it.

Tidal benefits:

The tide has many benefits, including:

1.fishing.

Fish may be concentrated during high tides. Commercial fishers are tracking the tides and learning to fish through higher levels of concentration to optimize their economic investments and make more efficient use of their time.Recreational fishermen may also fish during high tides because small fish populations attract larger fish.

2. Intertidal Zone Foods.

Crabs, mussels, snails, seaweed and other edible sea creatures inhabit the intertidal zone.Small tidal pools may also contain small fish and sea vegetables.

The marine life found in these areas is often harvested for food. Without the regular action of the tides, these complex organisms will die out and abundance and food resources diminish.

3. Mobility.

Tides affect depth and currents in and around coastal areas. Ships may need to sail in waters during high tide in some areas or risk being stranded. Pilots take into account the water level, the width of the channels, and the direction of the water flow to determine the best time to travel.

Pilots may choose to travel when the tides are ebbing in order to get long loads under bridges.

4. weather.

Tidal currents and tides affect weather by moving ocean water.Tidal currents mix Arctic waters that cannot absorb much sunlight with warmer waters do so. This shifting results in more predictable, habitable climate conditions and temperature balance on the planet.

5. Tidal Energy.

Two high tides and two low tides occur during a 24-hour period.The predictability of tides and the rapid movement of water during inbound and outflow can provide a source of renewable energy for communities living along the coast.

Hydroelectric plants can exploit water flow in ways similar to those used in rivers.

References :

“What is a tidal wave?”, oceanservice.noaa.gov

JENNIFER HORTON, “How Ocean Currents Work”، science.howstuffworks.com

Laura Klappenbach (8-3-2017), “How Do Tides and Waves Work?”، www.thoughtco.com

Kathryn Rateliff Barr (2017-4-25), “Importance of Tides”، www.sciencing.com

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