extra: waves Flashcards
Wave height
distance between the trough and peak of a wave
wave length
distance between two identical parts of different waves
wave period
time taken in between the part of the first wave passing a point and then that same point for the next wave
Zero up-crossing wave
a wave that crosses the average water level in an upward direction
Zero down-crossing wave
A wave that crosses the average water level in a downward direction
Where is wave energy derived from?
Wind by virtue of pressure differences either side of the wave crest
When is the process generating wave energy most powerful and when does it start to diminish and how?
Maximum translation in wave energy occurs when wind speed is 3x wave speed. Any additional wind speed is inefficient translation of energy and is wasted. Instead the wave crest now starts to dissipate and whitecap. However, the waves will nevertheless continue to grow in height just at a less efficient rate
What are the two types of wave in the process that generates waves?
Capillary waves and gravity waves
Capillary waves
like ripples on the surface of the ocean that are heavily influenced by local conditions. This is the infant stage of a wave and so at this point they are small in all their characteristics
Gravity waves
once capillary waves become big enough they can develop their own vertices (eddies). This means their restoring force now becomes gravity and they can grow a lot more from now
What are the main factors that affect the generation of waves?
Wind seed, wind direction, fetch, and duration
What is wave interference?
This is when two waves come in to contact with each other and their unique characteristics come together to influence one another in the form of a new wave
What would happen to two interfering waves of the same height, length and regime?
Because they are in sync this means that only the wave height doubles up and everything else remains constant
What would happen to two waves of the same height and length but inverse regime?
The regime is a key factor. The peaks of one set of waves would fill in at the point where the other waves have a trough and vice versa. This means that the waves effectively cancel each other out and the ocean becomes flat.
What would happen to two waves with completely different everything?
It depends on the characteristics exactly but there would be some form of equilibrium reached
What are sea wave conditions?
In the sea the waves are created and because there is very little else they are solely created based upon local conditions
What are waves like in sea conditions?
The local conditions are fairly disorganised and so the waves produced are quite chaotic.
What are the wave periods of waves generally in sea conditions?
Less than 8-10 seconds
What are waves like in swell conditions?
After a given time period of experiencing sea conditions, the waves will start to form a series of long-crested waves with now a narrower range of different characteristics between them
What happens to multiple waves in swell conditions?
They start to become a lot more similar
What are the general wave periods for waves in swell conditions?
More than 8-10 seconds
What causes waves to switch from their characteristics in sea conditions to those characteristics under swell conditions? Explain the process
Wave dispersion- waves are sorted out according to wavelength
What is a common trigger for wave dispersion?
Storm occurences
How does a storm trigger wave dispersion?
The storm forces waves out from the centre and this process, as with many things in nature, is intended to be as effective/efficient as possible and so the waves that have similar characteristics are grouped together
