Coastal Geography, Waves Flashcards
How do waves form?
From surface tension between air and water. Over time, these ripples become less agitated/choppy
Swell waves
Inital waves formed from wind that have become more organised over time
Storm waves
Locally generated waves that tend to be more volatile
What are the six main characteristics of wind waves?
Crest, length, frequency, period, velocity, and celerity
Wave crest
The highest point of a wave
Wave length
The distance between two wave crests
Wave frequency
The number of waves passing a fixed point each second
Wave period
Time required for two wave crests (one wave) to pass a fixed point
Wave velocity
The speed of the wave.
Wave length/wave period
Wave celerity
The speed of wave’s shape/phase velocity
What is the relationship between wave period and wave velocity
A positive, linear relationship. Consequently, a small increase in wave period results in a large increase in wave length
Surf beat
Alternating of high and lower set waves (like a heartbeat)
Orbital motion
Water particles rotate in closed orbits below waves
Wave base
The difference between deep and shallow water waves
Stokes drift
Water particles don’t return to precisely the same position once a wave crest passes
What four characteristics of a wave changes once it moves into shallow water?
Velocity, length, period, and crest
What happens to wave velocity in shallow water?
Velcoity decreases due to friction
What happens to wave length in shallow water?
Length decreases due to decrease in velocity
What happens to wave period in shallow water?
Period decreases due to shorter length
Wave shoaling
The increase in wave height when the wave base encounters the seafloor
What happens to the path of orbital motion in shallow waters?
The paths become flattened, causing them to kick up more sediment
Infragravity wave
The increase in water level caused from the changing momentum of wave sets
What type of wave is a tsunami?
Seismic seawave
What are the two relevant types of waves?
Spilling and surging waves
Spilling waves
Gentle waves that break softly over the shore. Occur in mildly steep slope beaches
Surging waves
Slow waves with long periods that don’t break but rather ‘roll’ onto the beach. Occur in steep slope beaches.
Fetch distance
The distance at which wave-generating winds blow.
Longer fetch = Larger waves
