WAVES LECTURE NOTES


VOCABULARY: oceanography; salinity; tide; tidal cycle; tidal interval; tidal range; high tide; low tide; spring tide; neap tide; flood tide; ebb tide; tsunami; storm surge; wave; current; upwelling; fetch; wave structure; trough; crest; wave height; wave length; period; wave speed; shoaling water; breaker; swash; backwash; rip current; undertow; beach; berm; bar; longshore current; beach drifting; groin; headland; bay; wave-cut cliff; notch; wave-cut terrace; wave-built terrace; marine terrace; sea cave; sea arch; stack; pebble beach; sand bar; offshore bar; spit; baymouth bar; tombolo; hook; lagoon; emergent; submergent; estuary; neutral; compound; harbor

OCEANS
study of the oceans is oceanography

salinity--average 100 pounds of sea water, 3 1/2 pounds of dissolved matter
would be higher but organisms remove lime and silica

salinity varies--less-heavy rainfall, diluted by ice, mouths of rivers; high-subtropics lots of evaporation

gases in water include CO2, oxygen; both important

temperature water freezes is 28°F because of salinity

tides--sun caused tides only about 44% as big as from the moon; tidal cycle is 24 hours 50 minutes; 2 high tides and 2 low tides a day; tidal interval is half as long
tidal range--difference
high tide--rises 6 hours 13 minutes; water toward coast
then it ebbs--water away until LOW TIDE
spring tides--sun, moon, earth in line; highest tides every 2 weeks
neap tides--lower than normal; at right angles; first 1/4 and third 1/4, every 2 weeks
flood tide--incoming
ebb tide--outgoing

tsunami--caused by seismic activity in ocean; long wave length
storm surge--high water level from hurricane

agent--waves
process--wave action


currents differ from waves
surface currents result from wind
density currents--saltier, colder, muddier, all more dense

Atlantic
•Atlantic Intermediate Waters--cold, dense, goes north, meets lighter, sinks, 2500' go north to 25°N to surface, upwells
• North Atlantic Deep Waters--next down, cold, dense, meet light warm water of Gulf Stream 7-13,000'
• Antarctic Bottom Waters--temperature cold, salt left from freezing, after cross equator, less defined, 20-40 years to reach equator, important because it carries oxygen down

wave--transfers energy through the water
waves caused by wind blowing across surface of ocean

characteristics of waves depend on: limited by friction and gravity

wave structure
trough
crest
wave length
wave height
period--time required for one complete wave to pass
wave speed--wave length / by period



energy and motion in deep water waves--as depth increases size of circle decreases; do not move, transfer motion from one to another; at depth half wave length, little motion

shoaling water--approach shore, water less deep, 1/2 wave length scrape bottom, energy of wave confined to smaller space, wave form lengthens, wave crests, o to O, bottom slowed--breaker

higher waves break farther out
as becomes shallower, height increases to wave height to length 1:7, gravity causes wave to collapse forward, breaking--breaker
swash--moves up on beach
gravity makes backwash back to ocean

rip current--strong surface current flow away from beach through breakers; undertow

wave erosion
when calm, builds shorelines
stormy, tremendous waves, enormous amounts of water against beach, lots of reshaping

wave action--berm formed by water crashing on shore, carrying material--winter steep, summer smooth
offshore bar--some flows in backwash and deposited, winter well developed, summer disappears

waves--strike shore at angles
2 processes occur
•1) longshore current in shallow water
•2) beach drifting--rock and sand particles on beach moved down beach in arched paths; groin stops movement

when shoreline not straight, waves refracted, concentrates energy on headland
headlands and promontories--project out
coves and bays--indentations


erosional shoreline features
wave cut cliff--deep water shore, erosion by waves
notch--erosion at water level
wave cut terrace (wave cut bench)--formed as wears back
wave built terrace--beyond wave cut terrace, material deposited offshore
marine terrace--a wave cut terrace or wave built terrace which has been raised above sea level
sea caves--rocks in highland different erosion, waves dig in, exposed at low tide
sea arches--waves cut through vertical joints or walls of sea cave
stack--roof collapses

depositional
beach--area between low and high tide, irregular shoreline in bays and coves

sand bars--parallel to mainland, high tide may cover
offshore bars--unattached
spit--sand bar attached to mainland projection
baymouth bar--clear across bay
tombolo--island to mainland
hook--end curved by waves
lagoon-area between offshore bar and mainland, protected

types of shorelines (Douglas Johnson)
Go to the Eolian, Arid, and Coast Block



Go to the Wave Review Questions

Go to the Glossary of Landform Terms



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