Unit 3: Waves and tides.
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Transcript of Unit 3: Waves and tides.
Unit 3: Waves and tides Part 1 -Lesson 23: Waves Teauhuapo Intro
to waves and tides
Prezi wave comparison https://prezi.com/lumawvrgyp9v/edit/#1_ Wave
demonstration Wave basics Where do ocean waves come from?
Anything through which energy flows is called a medium. Ex: metal,
string, water, land, air Wave basics Where do ocean waves come
from?
A disturbance caused by the transfer of energy through amedium is
called a wave. Source of energy for most waves is wind. Wave
Structure Crest highest part of a wave
Trough lowest partof a wave Wave Height Wave structure Wave height
verticaldistance between acrest and its nearesttrough. Amplitude
half of thewave height Wavelength horizontaldistance between
twocrests or troughs Wave Height WAVELENGTH= horizontal distance
(crest to crest)
WAVE HEIGHT = vertical distance (crest to trough) Wave basics If
you look at the ocean in a cross section, surface wave wouldlike a
transverse wave. Transverse wave motion of water is perpendicular
todirection of wave Wave basics Its actually an orbital wave water
is moving a circularmotion Orbital motion The size of the orbit of
thewater particles increaseswith wavelength The orbit size
decreasesrapidly with depth Only "feel" waves to a depthof 1/2 of
their wavelength Wave basics Longitudinal wave Motion of the water
moves parallel tothe flow of energy. Think slinky! Longitudinal
Transverse = 1 = 1
Wave calculations Period = time for wave to move 1 wavelength
Frequency = number of waves passing fixed point Inverse
relationship: = 1 = 1 Parts of a wave 20 seconds Period = time for
wave to move 1 wavelength
What is the period for the graph? a. b. 20 seconds Parts of a wave
Frequency = # of waves passing fixed point What is the frequency
for the graph? or 0.05 sec In 1 second, 1/20th of wave will pass
point or takes 20 seconds for complete wave to pass point (typical
wind driven ocean wave is 20 seconds or less) What affects wave
height?
a. Wind speed b. Wind duration c. Fetch WAVE HEIGHT = vertical
distance (crest to trough) What affects wave height?
1.Wind speed How hard wind blows changes energy transfer&
therefore wave height WAVE HEIGHT = vertical distance (crest to
trough) What affects wave height?
2.Wind duration How long wind blows changes energy transfer&
therefore wave height What affects wave height?
c.Fetch Amount of ocean surface area affected bywind blowing in the
same direction. What causes a wave to break? What affects how a
wave breaks?
Type of swell Wind direction Slope of sea bed Sea floor features
How does a wave break? Wave train approaches shore "feels" bottom
at depth = 1/2wavelength Bottom of wave slows even more as gets
shallower, wavecrest moves ahead of base of wave When depth of
water is of wave height, it will break. Deep water vs. shallow
water waves
Deep Water waves The wave occurs inwater deeper than halfthe
wavelength. Not affected byseafloor Shallow Water waves Waves enter
water thatis equal to or less than1/20 the wavelength Types of
Waves Spilling breaker: Found at gently sloping bottom.
Plunging breaker: Found at moderate sloping bottom. Surging
breaker: So steep that wave doesnt break until right at shoreline.
S Training to survive big waves More Types of waves Tsunami caused
byplate shift on seafloorcausing a majordisplacement ofwater
Malaysia tsunami Click Tsunami tsunami tsunami More Types of waves
Rogue waves Waves cometogether in positiveinterference Rogue waves
often involve more than two wave crests combining
Rogue waves often involve more than two wave crests combining. In
some cases, rogue waves seem to be generated when waves interact
with strong surface water currents. Researchers model rogue waves
as a non-linear process, meaning they do not involve simple wave
crest addition, but more complex interactions of wave energy Lesson
24: Tides Tides Causes Moons gravity Centrifugal force Suns gravity
The Sun affects the Earth because it is so large, while theMoon's
proximity to Earth is the main reason for its role in thetidal
cycle. High and low tide High Tide: Low Tide:
Occurs when the body of water is in linewith the moon. Highest
point water reaches onto shore. Low Tide: Occurs when the body of
water in perpendicular to the moon. Lowest point water reaches onto
shore. Tidal range:Distance between high and low tide.
Affected by moon phase. Organisms must adapt to tidal range.
Ex:Sea turtles lay their eggs above the highest high tide. Largest
tidal range in the world bay of fundy
Tidal range = 16m or 52 feet Tidal range This photo is a double
exposure(a photographic techniquewhere a film is exposed twice,thus
superimposing one imageon top of another) of the NOAAShip
Fairweather docked at apier in Anchorage, Alaska. Thetwo photos
were taken from thesame location, capturing theship at both high
tide and lowtide. The tidal range wasbetween 9 and 11 meters (~30
36 feet). Tidal movement Flood tide: Water moving onshore from low
to high tide.
Tide is coming in Tidal movement Ebb tide: Water moving offshore
from high to low tide.
Tide is going out Flood tide Ebb tide 3 basic patterns of
tides
Semidiurnal tide pattern Most areas on Earthexperience this type
Two high tides and twolow tides per day 3 basic patterns of
tides
Diurnal tide cycle One high and one lowtide per day 3 basic
patterns of tides
Mixed Tide pattern Two highs and twolows per day butone set of
tides ismore dramaticthan the other. 2 types of tides 1) Spring
Tide
Sun and moon line up andpull in the same direction Greatest tidal
variationbetween high and low Occurs twice a month New and full
moon tides 2)Neap Tide Sun and Moon are lined upperpendicular
(partiallycancelling each other out) Least tidal variation