waves Flashcards
1
Q
what is wavelength?
A
- horizontal distance between successive crests
2
Q
what is height of a wave?
A
- vertical distance between crest and trough
3
Q
what is period of a wave?
A
- time interval between succesive crestspassing a point
4
Q
example of generating force?
A
- wind stress
5
Q
example of restoring force?
A
- gravity
6
Q
what does energy/ size of wave depend on?
A
- wind speed
- wind duration
- fetch
- original sea state
7
Q
for large fetch and duration, size of wave depends on?
A
- only on wind speeds
8
Q
what are deep water waves?
A
- water particle orbits are circular
- forward beneath crest
- backwards beneath trough
9
Q
properties of deep water waves?
A
- particle orbits are closed
- no net flow of water
- energy and momentum transferred by waves
10
Q
properties of waves at surface and for larger waves?
A
- particle orbits are open
- net forwards flow of water (stokes drift)
- mass transport of water due to waves
11
Q
properties of shallow water waves?
A
- particles orbit influenced by seabed
- orbits compressed in vertical = ellipses
- to an fro motion at seabed
12
Q
storm winds are..?
A
- unsteady
- variable direction
13
Q
waves generated are…?
A
- forced waves
- irregular
- mixed characteristics
- known as SEA
14
Q
what is deep water wave formulae?
A
C = gT/ 2(pie)
15
Q
what is disprsion?
A
- waves become sorted by length
16
Q
properties of waves travelling in groups?
A
- propagate at group speed
- arise from interaction of waves with similar characteristics in deep water
17
Q
formula for group speed of waves?
A
Cg = gT/ 4(pie)
18
Q
what is shoaling?
A
- as waves enter shallowing water
- waves interact with seabed
- particle orbits are compressed
- waves slow down
- wavelength reduces
- waves steepen
19
Q
what is refraction?
A
- wave crests tend to be parallel to the shore
- for oblique incidence waves.. shallow end of wave slows first.. wave crest bends around
- refraction focuses wave energy towards shoals and headlands
- away from deeper areas and bays
20
Q
what is breaking?
A
- in very shallow water, waves become too steep
21
Q
different types of breaking?
A
- spilling
- plunging
- surging
22
Q
what is spilling?
A
- slow energy release
= flat beach
23
Q
what is plunging?
A
- rapid energy release
= steep beach
24
Q
what is surging?
A
waves breaks at shoreline
