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 Stirred by the winds into waves and pulled up and down by tidal forces, the ocean surface is always in motion.  Waves are among the most common and easily observed ocean phenomena.  Waves are periodic and predictable if the amount of energy applies to the ocean is known.  Predictable wind, earthquakes, turbidity currents, landslides, friction, and the pull of the sun and the moon all generate waves.  The sun and the moon generate the largest waves of all: the tides.

 Waves are energy transmitted through matter ◦ The medium ( solid, liquid, gas) not actually travel as the energy passes through it, but its constituent particles vibrate or oscillate in place as the energy passes through them.

 Longitudinal waves (push-pull) – sound waves, the particles that are in vibratory motion push and pull in the same direction the energy is traveling. ◦ Wave form travels through the medium by compressing and decompressing

 Transverse wave (side to side ) – energy travels at right angles to the direction of particle vibration ◦ Generally transmits energy only through solids because only in a solid are particles strongly bond to one another ◦ These are called body waves because they transfer energy though a body of matter

 Orbital waves – waves that transmit energy along an interface between two fluids of different densities ◦ Particle movements are neither longitudinal nor transverse ◦ Example: interface between the atmosphere and the ocean. The movement of particles along such an interface involves components of both longitudinal and transverse waves because the particles move in circular orbits.

 As a wave passes to the right, the motion of a floating rubber ducky resembles that of a circle, which is known as circular orbital motion

 Crest – high parts of waves  Trough – low part of waves  Wave height (H) – vertical distance between the trough and crest  Wave length (L) – horizontal distance between two corresponding points  Wave steepness- H/L

 Wave period – time (in seconds) that elapses during the passing of one full wave, or wavelength  Wave frequency- the number of wavelengths that pass a fixed point per unit of time  Amplitude- Distance from level of crest to level of trough

 Period- 

Practice!!! Wave length = 5m Height = 1m Frequency = 14/min Period = ? Speed = ? Steepness = ?

Practice!!! Wave length = 5m Steepness = 1/8 Frequency = 3/sec Height = ? Speed = ?

 Shallow-Water Waves  Depth of water is above wave base, way above. (depth < 1/20 wave length)

 Deep-Water Waves – Depth is deeper than wave base. (depth > ½ Wave Length)

 Transitional Waves (Between Deep and Shallow)  Depth is above wave base, but only a little. (1/2 wavelength > depth > 1/20 wave length)

 Recall: ◦ ◦ Wave Base = ½ Wave Length  Think:  What happens if the Wave Base is decreased?  How does that effect Wave Speed?  Breaking  Steepness = 1/7 = H/L

Effect of Decreasing Depth en&v=gxSDdaHzTJM&NR=1

 Any Guesses?

 Capillary Waves  The little guys  You’ve seen these on Lucky Peak  Gravity Waves  Can be huge  You’ve seen these in videos of the ocean, probably not on a lake.  Breaking waves  AKA: White Caps  Also on the shore  Any time the steepness is larger than what?

Wind Generated Waves Factors important to increasing the amount of energy transferred to the waves are: 1. The wind speed 2. The duration – the length of time during which the wind blows in one direction 3. The fetch – the distance over which the wind blows in one direction

Wind Generated Waves The energy of a wave is directly related to wave height As sea waves gain energy, their steepness increases When steepness reaches a critical value of 1/7, open ocean breakers called whitecaps form

 Swells from different storms run together, the waves clash, or interfere with one another

 Starts as a capillary wave in open sea.  Grows to a gravity wave.  The storm surges  The swell distances itself from the storm  Carries energy (in the form of waves) across the open sea. ◦ Can cause interference across the open sea  As deep water swell moves toward shore (shoaling) it enters the surf  Energy in the wave dissipates when the wave breaks.

Physical Changes as waves approach shore As deep water waves of swell move toward continental margins over shoaling water, they eventually encounter water depths that are less than one-half of their wavelength

Physical Changes as waves approach shore S waves come into shallow water and fell bottom, their speed and wavelength decrease while their wave height and wave steepness increase, this action causes waves to break Breaking waves are analogous to a person who leans too far forward.

Breakers Spilling breakers – is a turbulent mass of air and water that runs down the front slope of the wave as it breaks Plunging breaker – has a curling crest that moves over an air pocket Surging breaker- build up and break right at the shoreline.

Breakers

Rogue Waves Massive waves that can reach 10 stories high Impossible to predict occurrence, main cause of rogue waves is theorized to be extraordinary constructive interference

 Rouge waves:  Think they are Dangerous?

 Wave train  A series of waves  Is it really rare?

 Breaking  Steepness = 1/7 = H/L  If length decreases, and height increases, what happens to steepness?  Refracting Waves  If the shore is not straight, how does the differing speed effect the apparent direction of the wave?

 What do they do?  What are they?  Two – or three types.  Really there are only two but when combined they make a third that’s kind cool and that’s what ocean waves are, well, not all water waves, just the ones that we are used to seeing, I mean a tsunami is a wave, and made of water, and in the ocean, but its not an ocean wave, ocean waves are something more specific, and tsunamis aren’t the third kind of wave so much… But, all waves do the same thing, and what do they do?

 What are the TWO types of waves?  What do they add up to?  Which is an ocean wave?  What are some parts of a wave?  How deep does the motion of a wave go?

 Who can name some?

 Ocean Waves  Atmospheric waves  Internal waves – “desk top oceans”  Where do these happen?  Splash Waves  Tides  Tsunami  Human Induced

 Tsunami  What causes it?

 Tsunami  Storm Surge  Swell  Shoaling  Fetch  Wave train  Rouge Waves  Breaking Waves  Interference  Refracting Waves  Reflecting  Diffracting  Gravity Waves  Capillary Waves  Transitional Waves  Shallow-Water Waves  Deep-Water Waves

 Types of waves  Waves and Water Depth  Deep-Water Waves  Shallow-Water Waves  Transitional Waves  Breaking  Steepness = 1/7 = H/L  Refracting Waves  The Cause – Wind – fig 9.8, table 9-1,  Capillary Waves  Restoring force  Gravity Waves  Breaking Waves  Life of a Wave  Rarities  Rouge Waves  Interference  Wave train  Tsunami

 Create a diagram of a Wave Train which is shoaling.  Label the following parts:  Crest  Trough  Wave length  Wave height  Still water level  Wave Base  Open water waves  Deep water waves  Transitional waves  Shallow water waves  Breaking waves

 Wave length = 2m  Height = 1m  Period = 13 sec  Frequency = ?  Speed = ?  Steepness = ?

 Wave length = 5m  Height = 10m  Period = 4 sec  Frequency = ?  Speed = ?  Steepness = ?

 Wave length = 5m  Height = 10m  Period = 4 sec  Frequency = ?  Speed = ?  Steepness = ?