NOTES
Links to summaries of key issues for each topic
VISUALS
Links to images employed in lectures on a topic-by-topic basis
TEXT
Link to chapter outlines at online learning center at McGraw Hill.
NOTES
Links to summaries of key issues for each topic
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Notes on Topic:
The notes represent summaries
of key issues for each topic
They emphasize the terminology used to
describe the various phenomena.
| 1. Wave Characteristics: |
| Learning Objectives: |
- Comprehension of the forcing factors that generate waves
- Understanding of the principles applied to describe the features of
waves
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| How a Wave Begins: |
- Generating force: disturbance (wind, gravity, earthquake)
- Restoring force: surface tension, gravity (also Coriolis effect).
- Force: wind, creates ripples or capillary waves.
|
| Anatomy, Motion and Speed: |
- High point, crest and low point, trough
- Dimensions:
- wave height (H), wavelength (L), wave period (T), or amplitude (H/2)
- Water moves in circular orbits with slight forward displacement
- orbit size decreases with depth
- size of orbit at surface = to height
- orbit disappears at L/2 (wave base), no movement
- Speed, celerity (C = L/T), speed of individual wave.
|
| 2. Deep Water Waves: |
| Learning Objectives: |
- Appreciation of processes forming deep-water waves
- Understanding of wave movement in groups and their interference
- Recognition of factors that control wave height
|
| Storm Centers and Dispersion: |
- Progressive wind waves formed by persistent winds (e.g. trades)
- move away for storm centers
- build "sea".
- waves with long L and T travel faster
- leads to dispersion or sorting of waves
- creates wave trains, swell.
- storm centers at 40-50°S in Pacific create swell off Alaska.
|
| Group Speed and Wave Interaction: |
- Wave trains:
- group moves at half speed
- individual waves (V=C/2)
- leading waves lost as new waves form.
- Waves intersect and combine at sea
- may reinforce one another: constructive interference
- may cancel one another: destructive interference
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| Wave Height and Energy: |
- Height of waves depends on:
- wind speed, wind duration (time) and fetch (distance)
- limited by any of the three factors.
- Atlantic wave size is limited by fetch ~11m, Pacific up to 34m.
- sea described by Beaufort scale (0 - 12) dependent on wind strength.
- Episodic waves:
- rogue waves when waves combine, currents meet.
- Wave Energy:
- transmitted in two forms:
- potential (elevation)
- kinetic (movement of water)
- energy dissipated as heat.
- Wave steepness:
- steepness = H/L
- waves break when H/L = 1/7.
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Department of Geological Sciences,
1001 E. Tenth Street, Bloomington, IN 47405-1403
Phone: (812) 855-5582 Last updated: 7 December 2000
Comments: simon@indiana.edu
Copyright
2000, The Trustees of Indiana University
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