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