All About Waves Notes

All About Waves Notes

The coast is a narrow contact zone between land and sea.

-A wave is a long curled body of water that arches and breaks when it reaches shore. The cause of a wave is the transfer of energy from the wind on the surface of the water.

-Larger waves are formed when winds are strong, blow for long periods of time across large areas of water.

-The max distance of water over which winds can blow is called the fetch

How a wave is formed:

Step 1: Wind blows upon a surface of water, the water particles in the wave move in a circular motion.

Step 2: As the seabed become more shallow the friction between the seabed causing the base of the wave to slow down

Step 3: The top of the wave unaffected by friction increases in height and steepness and the wave starts to topple over called “breaking” The swash, the remnant of the wave moves energy forward, while the backwash transfers energy back.

There are two types of waves:

Constructive

-Created in calm weather

-Break on shore and deposits materials

-Stronger swash compared to backwash

-Long wavelength, low height

Destructive

-Created in stormy weather

-Are created from big, strong waves when the wind is powerful and has been blowing for a long time.
-Occur when wave energy is high and the wave has travelled over a long fetch.

-Tend to erode the coast.
-Have a stronger backwash than swash.

- a short wave length and are high and steep.






How can waves erode the earth?

Hydraulic action: lots of sea water crashes against the land, causing air and water to become trapped and compressed in surface cracks. When the sea retreats the air expands, weakening the cracks in the rock and causing pieces of the rock to break off. 
Corrasion: caused by bits of rock hitting the cliffs and other parts of the land, causing more bits of rock to break off. 
Attrition: rock fragments grind each other down into smaller and smoother pebbles and eventually into sand which is then deposited on the beaches. 
Corrosion: involves the chemical action of sea on rock, often happens with limestone beaches, when the limestone dissolves in the sea water although the salt can affect some other stones as well.