Chapter 10 + 11 - Waves and Tides

It’s a common misconception waves transmit water mass. What do they actually transmit across the ocean?

Energy

How are ocean waves classified?

• the disturbing force that creates them

• the extent to which the disturbing force continues to influence them once they are formed

• their wavelength

Celerity

swiftness or motion of a wave. proportional to its wavelength

Why are tsunamis and tidal waves always in shallow water?

their wavelength is too great

Waves

disturbances caused by the movement of energy

• energy is moving, not water

Orbital waves

energy is transferred via circular motions

Progressive waves

waves that “move” forward. obtain a curve over time

How are waves classified by their physical characteristics?

• Formed by disturbing force

• Restoring force – flattens water surface

• Wavelength – most useful measure of wave size

Deep water waves

depth greater than ½ wavelength

• C = L/T

Shallow water waves

depth less than ½ wavelength

• C = 3.1vd

Wind waves

wind energy transferred to water

Capillary waves

small, free, surface-water waves with such short wavelengths that its restoring force is the water's surface tension. forms from friction

What factors affect the growth of a wind wave?

• Wind strength

  • Affects wave height

• Wind duration

  • With longer wind time, waves have more time to build energy and grow larger

• Fetch

  • Determines the size of waves produced

Fetch

the uninterrupted distance over which the wind blows without significant change in direction

Destructive interference waves

two waves collide and cancel each other out

Constructive interference waves

two waves collide and combine

Rogue wave

large and unpredictable surface waves that can be extremely dangerous to ships and isolated structures such as lighthouses. usually caused by interference

Storm surge

abrupt bulge of water. short lived, only consist of a crest

Tsunami

long-wavelength, progressive waves which are caused by the rapid displacement of water. these are shallow, they move quickly, and are destructive and dangerous on land

What does the speed of a wave depend on?

wavelength

What does wave behaviour depend on?

the relation of wave size to depth of water

Tides

periodic short-term changes in ocean surface height at a particular place

Where does the biggest tide change in the world occur?

Bay of Fundy

The strength of attraction between Earth and the moon is…

Equal

The water forms a _____ on either side of the Earth

Bulge

How many high and low tides are there every 24 hours?

Two for each tide level

How much later are high tides than the one the day before?

50 minutes later

Dynamic theory

a set of concepts that describe behavior as the emergent product of a self-organizing, multicomponent system evolving over time. adds fluid motion to celestial mechanics to the equilibrium theory

Semidiurnal tides

a common tidal pattern that occurs twice in a lunar day

Diurnal tides

a common tidal pattern that occurs once in a lunar day

Mixed tides

a common tidal pattern where two high tides and two low tides occur per day, but the heights of each tide differs; the two high tides are of different heights, as are the two low tides

Amphidromic point

a place where the tidal range (difference in height between high and low tide) is zero compared with other areas in the basin. no tide

Tidal datum

a standard elevation defined by a certain phase of the tide. reference point of tidal height. not always sea level

Tidal range

the difference in height between high tide and low tide. differs with basin configuration

Tidal bore

steep wave moving upstream at some inlets

Meteorogical tides

• weather related alterations

• storm surge

• tsunami

• strong on-shore wind

How can tidal patterns affect marine organisms?

• Some organisms live between the high and low tide zone (intertidal zone)

• Sorted into subzones within the intertidal zone

Seiche

a temporary disturbance or oscillation in the water level of a lake or partially enclosed body of water, especially one caused by changes in atmospheric pressure. a rocking wave

Deep water vs. shallow water waves

• Deep water waves: depth is greater than ½ wavelength

• Shallow water waves: depth is less that ½ wavelength

What causes tides?

gravity from the sun and moon, motion of the Earth, and inertia of water

Spring tide

refers to the 'springing forth' of the tide during new and full moon

Neap tide

refers to a period of moderate tides when the sun and moon are at right angles to each other

Intertidal zone

the area where the ocean meets the land between high and low tides