Transcript Waves Waves  Wave: A periodic disturbance in a solid, liquid, or gas as energy is transmitted through a medium (such as.

Waves
Waves
 Wave: A periodic disturbance in a solid, liquid, or gas
as energy is transmitted through a medium (such as air,
water, or rock).
Wave Structure
 The crest is the highest point above the equilibrium
position, and the trough is the lowest point below the
equilibrium position.
 The wavelength () is the distance between two
adjacent similar points of a wave.
Wave Formation in the Ocean
 What do you think causes most
waves in the ocean to form?
 Answer: Wind!
 The longer wind blows, the more
energy is transferred to the
ocean’s surface causing a wave
to form.
Types of Waves
 Wind Waves- usually less than 3 meters high.
 Capillary wave- ripples that turn into wind waves.
 Seiche- water confined to a small space like a bay will
slosh back and forth at resonant frequency.
 Tsunami- Seismic wave created by an earthquake on
the ocean floor.
 Tides- caused by gravitational pull on the earth by the
moon and sun.
Wave Movement
 Energy in a wave only moves
up and down in a circulartype motion.
 Energy does not travel
laterally (side to side).
 This is why you move up and
down as a wave moves past
you.
Wave
Wave Heights
Factors Affecting Wave
Development
 1.) Mean Speed or Wind Strength- Wind must be moving
faster than the wave crests for energy to transfer from air to
sea.
 2.) Wind Duration- High winds that blow only a short time
will not generate large waves. Low winds that blow for a
long time can generate very large waves.
 3.) Fetch- uninterrupted distance over which the wind blows
without significant change in direction.
 Strong wind must blow in one direction for 3 days for large
waves to be fully developed (called a fully developed Sea)/
Wave Interference
Rogue Waves
 Caused by positive (in phase) interference) of waves in
open ocean.
 Until recently, thought to be impossible.
Breaking Waves
 What causes a wave to crest
or “break?”
 Answer: As wave approaches
the coastline, the slope is
shallower.
 The bottom of the wave drags
along the floor slowing it
down.
 The top of the wave continues
at it’s previous speed causing
it to go faster than the bottom.
 This makes the wave break.
Wave Refraction
 Slowing and bending of
waves in shallow water.
 Caused due to waves hitting
shoreline at an angle.
 This is why waves break at
different points as they
approach the shoreline
Wave Diffraction
 Wave changing direction due to an obstacle like a
breakwater or jetty.
Wave Reflection
 Waves will reflect if they hit an object straight on.
 Will cause minor constructive interference.
Undertow and Rip Currents
 Undertow: Formed when water
breaking onto a beach is pulled
back into deeper water by gravity.
 Rip Currents: Form when there is
a break in a sand bar. Water is
quickly funneled out to sea.
 Rip Currents can flow from 1-8
feet per second. That’s faster
than an Olympic swimmer!
 How do you escape a rip current?
 Swim parallel to the shoreline!
Longshore Currents/Drift
 Longshore Current: Form
when waves approach the
beach at an angle.
 Sand is moved by these
currents forming sandbars
and spits.
 Often called longshore drift.
Longshore Drift