5. Wave characteristics
Frequency = how often the wave repeats itself (cycles) in one second.
Frequency = cycles per second = Hertz (Hz)
e.g., 4 Hz = 4 cycles /second
1st
1 sec.
4th
6. Wave characteristics
Period = the time it takes for a wave to complete one cycle.
period
.01
Time (sec.)
e.g., Period = 10 sec
Frequency = 1 = .10 Hz
10
Formula:
f = 1
p
p = 1
f
High frequency = small period
Low frequency = large period
10 20
21. Wave refraction
• Wave refraction
• Bending of a wave
• Causes waves to arrive nearly parallel to
the shore
• Consequences of wave refraction
– Wave energy is concentrated against the
sides and ends of headlands
– Wave energy is spread out in bays and wave
attack is weakened
– Over time, wave erosion straightens an
irregular shoreline
24. When do waves break?
– Limited by ratio between wave height and wave
length (H/L)
– Limiting steepness 1/7
How are they predicted?
– wave forecasting (or hindcasting) depends on
wind velocity, duration, and fetch (WaveWatch III)
– Linear wave theory predicts wave heights
Breaking Waves
http://polar.ncep.noaa.gov/waves/wavewatch/
37. Wave periods
• Larger wave period = higher energy = higher wave
• Wave height is limited by ratio between wave
height and wave length (H/L)
• Limiting steepness 1/7
