Ch3- Waves

Question 1

Wind waves

Answer 1

Generated by the wind blowing at the position considered

Question 2

Swell waves

Answer 2

Former wind waves that have travelled out of the area of generation, or continue in an area after the wind causing them has ceased

Question 3

How are waves formed?

Answer 3

• Air moving over the surface of the water exerts a drag upon it
• Air movement is turbulent and the drag upon the water surface fluctuates
• Waves form in the water surface that react with the airflow

Question 4

Period (s)

Answer 4

The time taken between passage of one crest past a point and the passage of the next crest

Question 5

Speed (kts)

Answer 5

The speed of movement of the wave crest through the water

Question 6

Length (m)

Answer 6

The distance from the crest of one wave to the crest of the next wave

Question 7

Height (m)

Answer 7

The vertical distance between crest and trough of a wave

Question 8

What is the shape of small waves?

Answer 8

Sinusoidal

Question 9

What does the shape of a wave change to, as the height increases?

Answer 9

Trochoidal

Question 10

What affects the height, length, speed and period of waves? (3)

Answer 10

Wind speed, duration and fetch

Question 11

What is the steepness of a wave?

Answer 11

The ratio of height to length

Question 12

How many descriptions of sea state are there? Name them.

Answer 12

11. Calm
12. Rippled
13. Smooth
14. Slight
15. Moderate
16. Rough
17. Very rough
18. High
19. Very high
20. Phenomenal

Question 13

How does wind speed affect wind wave height?

Answer 13

Governing the energy available for wave generation

Question 14

How does duration affect wind wave height?

Answer 14

The length of time over which the sea is influenced by the wind

Question 15

How does fetch affect wind wave height?

Answer 15

The distance over which the wind affects the sea

Question 16

Define fetch

Answer 16

The length of water over which a given wind has blown without obstruction.