1. Wave refraction

2. By the end of this lesson,
you will be able to...
1. Describe how waves approach a coast
with headlands and bays.
2. Explain how wave refraction happens
3. Explain how wave refraction results in
erosional and depositional features.

3. If you see these....
Think of the possible Add these
answers first before information into
checking the answer in pg 9 of your
the next slide handout

4. Wave refraction

5. What is
refraction?
Wave refraction

6. Remember what is
light refraction?
You’ve learnt it in
Sec 1 / 2 science
remember?

7. When Light
enters a
glass block...

8. It bends and
refracts!
When Light
enters a
glass block...

9. It bends and
refracts!
When Light
enters a
glass block...
Why did it refract?

10. When Light
enters a
glass block...

11. When Light
enters a
glass block...
It slows
down

12. When Light
enters a
glass block...
It slows
down
Therefore it
bends and
refracts

13. When Light When it
enters a exits the
glass block... glass block
It slows
down
Therefore it
bends and
refracts

14. When Light When it
enters a exits the
glass block... glass block
It speeds up
It slows again.
down
Therefore it
bends and
refracts

15. When Light When it
enters a exits the
glass block... glass block
It speeds up
It slows again.
down
Therefore it
bends back
Therefore it to its
bends and original
refracts angle.

16. So, what is refraction?
Change in direction /
bending due to
changes in speed.

17. So, what is refraction?
Change in direction /
bending due to
changes in speed.
What is wave
refraction then?
Think and write it into
your notes (Pg 9)

18. How does wave
refraction occur?

19. How do the waves travel when the coastline
is straight?

20. How do the waves travel when the coastline
is straight?
Almost
Parallel
Manner

21. How do the waves travel at headlands and
bay?

22. How do the waves travel at headlands and
bay?
Away from
the
headlands,
the waves
are almost
parallel to
each other.

23. How do the waves travel at headlands and
bay? As it
approach
the
headlands,
it begins to
bend.
Away from
the
headlands,
the waves
are almost
parallel to
each other.

24. How do the waves travel at headlands and
bay? As it
Bends approach
towards the
the headlands,
headlands, it begins to
bends bend.
away from
from the
Away from
sea
the
headlands,
the waves
are almost
parallel to
each other.

25. How do the waves travel at headlands and
bay? As it
Bends approach
towards the
the headlands,
headlands, it begins to
bends bend.
away from
from the
Away from
sea
the
headlands,
the waves
are almost
parallel to
each other.

26. How do the waves travel at headlands and
bay? As it
Bends approach
towards the
the headlands,
headlands, it begins to
bends bend.
away from
from the
Away from
sea
the
headlands,
the waves
are almost
Wave Refraction parallel to
occurred? each other.

27. How did
Wave refraction
occur?
why do waves refract?

28. ????
??? Land Legend
(Label it yourself
Wave
please)
Crest
???
??? (Label it yourself
(Label it yourself please)
please)
Sea

29. Change in direction /
bending due to
changes in speed.
Wave refraction

30. Where is the change in speed?
How is the speed changed?

31. Where is the change in speed?
How is the speed changed?
Parallel
= Same
Speed

32. Where is the change in speed?
How is the speed changed?
Slow
Slow
Down
Down
Parallel
= Same
Speed

33. Where is the change in speed?
How is the speed changed?
Speed
remains
Slow
Slow
Down
Down
Parallel
= Same
Speed

34. Where is the change in speed?
How is the speed changed?
Speed
remains
Slow
Slow
Down
Down
Parallel
= Same
Speed
Can’t Imagine how?

35. What could have changed the
speed of the waves?
Speed
remains
Slow
Slow
Down
Down

36. What could have changed the
speed of the waves?
Friction with the Seabed
Speed
remains
Slow
Slow
Down
Down

37. What could have changed the
speed of the waves?
Friction with the Seabed
Less
friction
More More
friction friction
Speed
remains
Slow
Slow
Down
Down

38. What does this indicate about
the depth of the water in front of
the headlands and bays?
Less
friction
More More
friction friction
Speed
remains
Slow
Slow
Down
Down

39. What does this indicate about
the depth of the water in front of
the headlands and bays?
Deeper
Shallower Shallower
Less
friction
More More
friction friction
Speed
remains
Slow
Slow
Down
Down

40. Let’s put this into a paragraph to explain how wave refraction happens
Near Near Bay
headland Deeper
Shallower
Less
friction
More
Approaching
friction
Speed Waves
remains Same depth
Slow
Down
Parallel
= Same
Speed

41. Let’s put this into a paragraph to explain how wave refraction happens
1) As the waves approach
the coast, they travel in a
straight line, parallel to
each other, as they travel in
the same speed.
Near
headland Approaching
Shallower Near Bay Waves
Deeper Same depth
More Less
friction friction
Parallel
Speed = Same
Slow Speed
remains
Down

42. Let’s put this into a paragraph to explain how wave refraction happens
1) As the waves approach
the coast, they travel in a 2) However, as the front of
straight line, parallel to the headland is shallower
each other, as they travel in than the front of the bay,
the same speed. the waves encounter more
Near friction and it slows down.
headland
Shallower Near Bay
Deeper
More Less
friction friction
Speed
Slow
remains
Down

43. Let’s put this into a paragraph to explain how wave refraction happens
1) As the waves approach
the coast, they travel in a 2) However, as the front of
straight line, parallel to the headland is shallower
each other, as they travel in than the front of the bay,
the same speed. the waves encounter more
friction and it slows down.
Near Bay
Deeper 3) As the front of the bay is
deeper than the front of
Less
the headland, the waves
friction
encounter less friction and
its speed remains.
Speed
remains

44. Let’s put this into a paragraph to explain how wave refraction happens
1) As the waves approach
the coast, they travel in a 2) However, as the front of
straight line, parallel to the headland is shallower
each other, as they travel in than the front of the bay,
the same speed. the waves encounter more
friction and it slows down.
4) This cause the wave to 3) As the front of the bay is
refract, where the waves deeper than the front of
bend towards the the headland, the waves
headlands and bends away encounter less friction and
at the bay. its speed remains.

45. ????
??? Land Legend
(Label it yourself
Wave
please)
Crest
???
??? (Label it yourself
(Label it yourself please)
please)
Can we
improve
diagram this
? To ma
explana ke theSea
tion cle
arer?

46. ????
??? Land Legend
(Label it yourself
Wave
please)
Crest
???
??? (Label it yourself
(Label it yourself please)
please)
Sea
??? ??? ???
(Annotate it (Annotate it
yourself please) (Annotate it
yourself please) yourself please)

47. By now you should be able
to
1. Describe how waves approach a coast
with headlands and bays.
2. Explain how wave refraction happens

48. Push your understanding further...
Wave refraction
How does it affect the energy?

49. Land
If the waves
were to bend
towards the
headland, will
Sea
the energy
become more
or less
concentrated?

50. If the waves
were to bend
Land away at the bay
will the energy
become more
or less
concentrated?
If the waves
were to bend
towards the
headland, will
Sea
the energy
become more
or less
concentrated?

51. Because of how wave refraction changes the energy
of the waves at the headlands and the bays,

52. Because of how wave refraction changes the energy
of the waves at the headlands and the bays,
What kind of features will you see at headlands?

53. Because of how wave refraction changes the energy
of the waves at the headlands and the bays,
What kind of features will you see at headlands?
What kind of features will you see at bays?

54. end of lesson