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GLY150:
INTRODUCTION TO OCEANOGRAPHY
University of North Carolina Wilmington
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Lecture
Outline
Waves
I. Wave
Characteristics
- Waves
at the Ocean Surface
- Orbital
motion
- At
surface diameter equals waveheight
- Decreases
with depth
- Slight
net transport
- Properties
of waves
- Crest
& trough
- Wavelength,
L
- Wave
height & steepness= H/L
- Period,
T
- Frequency,
f
- Speed,
C
- Depends
on wavelength, water depth
- Long
wavelength waves travel
faster than short
wavelength waves
- Deep-water
waves
- Wavelength
greater than twice wave depth
- Circular
motion of particles
- Shallow-water
waves
- Wavelength
greater than twenty times wave depth
- Elliptical
motion of particles
- Ellipticity
increases with depth
- Interaction
with sea bottom
- Transitional
waves
II.
Wind-Generated Waves
- Deep-Water
waves
- Sea
- Capillary
waves
- gravity
waves
- Fetch
- Duration
of wind blowing in same direction
- Strength
of wind
- Swell
- Wave
dispersion
- Wave
trains
- Shallow-water
waves
- Effects of
sea bottom interaction
- Wavelength
decreases
- Wave
speed decreases
- Wave
height increases
- Surf
- Wave
steepness > 1/7
- Breakers
- plunging
- spilling
- surging
II. Wave
Interaction
- Interference
patterns
- Constructive
- Destructive
- Mixed
- Interference
patterns near shore
III.
Non-Wind- Generated Waves
- Free
standing
- Form by
wave reflection
- Non-orbital
motion, lateral and vertical motion only
- Internal
- Form at
interface between two fluids of different
densities
- pycnocline
- Tsunami
- seismic sea wave
- Form from
submarine faulting, mass wasting, volcanic
eruption
- Wavelength
~200 km
- Wave speed
up to 800 km/hr
- Wave
height
- Open
ocean 0.5 m
- Coasts
up to 30 m
- Tides
- Form from
earth-moon-sun gravitational and centrifugal
forces
Some
helpful links relevant to these lectures:
Wave heights and
wind speed measured from satellites
Surfrider Foundation USA
East Coast Surf
Web
The Surf Page
Tsunami Research at the USGS
Tsunami Visualizations
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