Waves

Question 1

Give a brief description of the breaking of a wave

Answer 1

1. Prevailing wind created friction with sea resulting in circular motion underwater
2. Creates small troughs and crests
3. Further travels more energy is carried
4. Reaches shallower area waves back up due to friction creating elliptical motion (wavelength decreases, wave height increases)
5. Wave reaches coast, increases in height until it can no longer support its own weight, causing the wave to break (plunge line)

Question 2

At what ratio do waves break at?

Answer 2

1:7

Question 3

Define fetch

Answer 3

Distance over which the wind blows over the sea. Larger fetch gives more power and larger waves

Question 4

What are constructive waves?

Answer 4

Low energy waves tend to occur during summer when wind speeds are lower

Question 5

What do constructive waves contribute to the formation of?

Answer 5

Beach ridges and berms

Material is moved up beach due to strong swash

Question 6

What are destructive waves?

Answer 6

High energy waves tend to occur during winter due to more common storm conditions

Question 7

What do destructive waves result in?

Answer 7

Net loss of sediment and increasing gradient

Plunging motion creating a power backwash transporting sediment

Question 8

Give the characteristics of constructive waves

Answer 8

Height: Low; Less than 1 metre
Length: Long; Upto 100 metre
Steepness: Gentle
Period: Long
Fetch: Short
Frequency: 6-8 per min

Question 9

Give the characteristics of destructive waves

Answer 9

Height: High; Over 1 metre
Length: Short; 20 metres
Steepness: Steep
Period: Short
Fetch: Long
Frequency: 10-14 per min