Physics of surfing
videos
• Science of Big Waves (KQED)
• Garrett McNamara w/ GoPro, 90’+
• Teahupoo raw 2013
The energy of a
wave travels ahead
but the water
itself does not
Why are there consistently bigger
waves in the Pacific?
Factors determining wave power:
wind v, wind duration, and fetch
Why are the conditions so different?
Ground swell vs. wind swell
Seafloor determines wave (shape)
Wave energy consolidates due to
DIFFRACTION
To what depth would a
seasick scuba diver
have to go for relief?
Breakers form
In roughly ½ of
the wavelength.
So if there is a
longer period,
you have bigger
waves.
What is shown here?
So what are ideal surf conditions?
So what are ideal surf conditions?
• Wind: off-shore, not too strong
So what are ideal surf conditions?
• Wind: off-shore, not too strong
• Period: long (ground swell)
So what are ideal surf conditions?
• Wind: off-shore, not too strong
• Period: long (ground swell)
• Tide: dependent on particular break location
So what are ideal surf conditions?
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Wind: off-shore, not too strong
Period: long (ground swell)
Tide: dependent on particular break location
Substrate: sudden rise, reef, often a point
how heavy is a big wave?
> 1 ton per 1
3
m
Forces in balance while riding
Useful sites
• Magic Seaweed
• Surf-forecast.com
Other types of waves
CAPILLARY WAVES
A seiche is a standing wave in an enclosed or
partially enclosed body of water.
Seiches have been observed on lakes, reservoirs,
swimming pools, bays, harbors and seas.
A tsunami (at one time incorrectly referred to as a
tidal wave), is a series of water waves caused by the
displacement of a large volume of a body of water,
usually an ocean.
Created by: Earthquakes, volcanic eruptions and other
underwater explosions, landslides glacier calvings and
meteorite ocean impacts
2004 Indian Ocean Tsunami - Indonesia 35 meters high on shore - 176,000 fatalities
Diffracted around world, even to RI
Tsunami videos
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Japan 2011-raw: video
Japan 2011: National Geographic
Tsunami 101: National Geographic
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Cartoon overview of tsunami:
http://www.penmachine.com/podcast/audio/Entries/2008/3/5_Tsunami_video_from_VFS.html
2 interactives of 2004 tsunami:
http://www.pbs.org/wgbh/nova/tsunami/
See 1st chapters of America’s Tsunami: Are We Next?
How Stuff Works.com
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2004 first waves: http://videos.howstuffworks.com/discovery/27966-assignment-discovery-first-waves-of-2004-tsunami-video.htm
How the 2004 tsunami happened: http://videos.howstuffworks.com/discovery/27965-assignment-discovery-how-the-2004tsunami-happened-video.htm
2004 Plate shift: http://videos.howstuffworks.com/discovery/14049-tsunami-2004-indian-ocean-plate-shift-video.htm
2004 teletsunami, India: http://videos.howstuffworks.com/discovery/27976-assignment-discovery-teletsunami-video.htm
Pacific Warning System: http://videos.howstuffworks.com/discovery/27978-assignment-discovery-pacific-warning-systemvideo.htm
Tsunami warning system: http://videos.howstuffworks.com/discovery/29454-assignment-discovery-tsunami-warning-systemvideo.htm
Mega Tsunami: http://videos.howstuffworks.com/discovery/27977-assignment-discovery-mega-tsunami-video.htm
Megatsunami videos
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Alaska
Deep Impact
Could RI be hit tomorrow?
La Palma, Canary Islands (no sound)
Celerity (another name for speed)
C = L/T
L = wavelength (m)
C = 1.25√L
d = depth (m)
C = 1.56 T
C = celerity (m/s)
C = √gd = 3.1√d
T = period (s)
Wind Waves (deep)
Seismic Waves (shallow)
Period ≈ 20 seconds
Period ≈ 20 minutes
L to ≈ 600 m
L to ≈ 200 km
So C can reach 112 km/hr
So C can reach 760 km/hr