Wave Refraction

Question 1

Why do waves not approach a straight uniform coastline

Answer 1

It is very rare for waves to approach a straight uniform coastkunr, as most coastlines have a variety of bays, beaches and headlands

Question 2

Because of these features along the coastline what happens the sea water

Answer 2

Because of these features, the depth of sea water sound a coast varies and as a wave approaches a coast its progress is modified due to friction from the sea bed

Question 3

When does the base of the wave start to feel friction

Answer 3

When sea depth is 1/2 the approaching waves wavelength, shown in s2 on my diagram

Question 4

What happens the wave around the shallower headland

Answer 4

The base of this wave around the shallower headland slows down whilst the other sections of the wave continue undisturbed

Question 5

What is the result of different sections of the wave flowing at different speeds

Answer 5

The wavefront has now been modified and it no longer runs parallel to the coastline

Question 6

What then happens when the wave continues to approach the coast

Answer 6

As the wave continues to approach the coast, shown in s3 on my diagram the wave starts to become refracted around the headland and this results in the wave energy being concentrated around the headland

Question 7

What happens the wave right along at the headland

Answer 7

At s4 in my diagram the wave section along the headland has reached the crustal point of depth

Question 8

What is the critical point of depth

Answer 8

The critical point of depth is less than 1/20th of the wavelength and as such has ‘broke’ onto the headland and released its energy there

Question 9

What happens the remaining section of the same wave

Answer 9

The remaining section of the same wave continues onto the Bay Area

Question 10

What helps show how energy released is not uniform along a coast

Answer 10

Orthogonals

Question 11

What are orthoganals

Answer 11

Lines drain at right angles to the wave crests that help show how energy released is not uniform along a coast

Question 12

What does wave refraction result in

Answer 12

Results in concentrated wave energy on headlands and energy dissipation into bay areas, creating local differences and making Hugh energy and low energy sections on the same coastline

Question 13

What are local examples of wave refraction

Answer 13

Portrush, NI
Here the prevailing westerly winds drive the waves to refraction around Ramore Head and dissipate their energy into the East and West strand areas on either side