OCNG 251 Exam 3 Study Guide Summary of Emails Invasion of Lionfish Lionfish have increased eating other reef fish and mollusks and attacking commercially important species like grouper and snapper Ideas so far to reduce the amount of Lionfish 1 Hunt them 2 Eat them 3 Train sharks to eat them 4 Stop importing 5 IPhone App Partial Eclipse The Moon will passed in front of the Sun on October 23 and what we saw was a partial solar eclipse but remember never look at the sun without proper filters Megalodon Scientists now have a better theory on how megalodon a giant 60 ft shark went extinct they estimated it to be about 2 6 million years ago Ch 8 Waves I Wave nomenclature wavelength period height steepness frequency speed Wavelength The distance from any point on a wave to an identical point on the next wave Trough to Trough Crest to Crest etc Period The time between two successive waves Height The vertical distance between crest and trough is the wave Steepness The ratio of wave height H to wavelength L Frequency The number of waves produced in a given amount of time Speed The rate of which a wave travels Wavelength divided by period II Wave types capillary gravity wind tsunami internal standing Capillary Wave waves have wavelengths less than about 1 74 cm 0 7 in and surface tension is the major restoring flattening force o Sailors call these catspaws Gravity Wave waves have wavelengths more than about 1 74 cm 0 7 in and gravity controls wave propagation and restoration Wind Wave Capillary and gravity waves are wind driven Tsunami Wave Caused by seafloor earthquakes Referred to in popular press as tidal waves but tsunami have nothing to do with tides Internal Wave Density interfaces occur within the ocean and not just at the air sea interface internal waves can reach heights of 100 m 330 ft Standing Wave Standing waves are the result of two waves of the same length moving in opposite direction Happens in closed basins when waves reflect off basin walls e g bathtub slosh III Characteristics of waves in deep water and shallow water speed particle motions Deep Water Water depth d is greater than one half of the wavelength are not affected by they don t feel the ocean bottom speed depends only on the wavelength VI Shallow Water Depth of the water is less than 1 20 of the wavelength are influenced by the water depth and they do feel the bottom Wind generated waves sea swell surf and breakers Sea A portion of the ocean where waves are being generated by wind Swell A free ocean wave by which energy put into ocean waves by wind in the sea is transported with little energy loss across great stretches of ocean to the margins of continents where the energy is released in the surf zone Surf zone The near shore zone of breaking waves Breaking Waves that break in the surf zone because particle motion near the bottom of the wave is severely restricted slowing the waveform V Factors determining the growth of wind waves wind speed duration and fetch Wind Speed Duration The length of time which the wind blows in one direction Fetch The distance over which the wind blows in one direction VI Concept of a fully developed sea A fully developed sea is found when waves do not continue to grow i e the waves lose energy at the same rate as energy is supplied by the wind VII Interference patterns and rogue waves Interference patterns The overlapping of different wave groups either in phase constructive interference which results in larger waves out of phase destructive interference which results in smaller waves or some combination of the two mixed interference VIII Rogue Waves Rogue waves are waves that can reach 30m or more in height Thought to occur from constructive wave interference e g Perfect Storm Especially dangerous in areas where large wind waves encounter strong currents e g Agulhas Current or the Gulf Stream Refraction and reflection of waves Refraction Waves typically do not approach beach at a perfect right 90 angle Part of wave that feels bottom first will slow down Waves bend towards shallow water Reflection In a system with walls can form standing waves Waves need correct wavelength frequency IX In harbors these resonances are known as seiches Standing waves and the bathtub slosh Standing Waves The sum of two waves with the two waves with the same wavelength moving in opposite directions resulting in no net movement Bathtub Slosh Happens in closed basins when waves reflect off basin walls e g bathtub slosh a k a seiche Tsunami storm surges and internal waves Tsunami A seismic sea wave A long period gravity wave generated by a submarine earthquake or volcanic event Storm Surges When long fast waves surge ashore they can do a lot of damage Internal Waves A wave that develops below the surface of a fluid the density of which changes with increased depth Ch 9 Tides I Orbital mechanics Newton s gravitation and centripetal force Every object in space is attracted to every other object by a force called gravity Objects in motion follow a straight line path unless acted on by an unbalanced force Centripetal force is the inward pull you exert on the string to keep the ball moving in a circular path II The tide generating force and the tidal egg The tide generating force the difference between the gravitational attraction and the centripetal force acting on the water in the ocean III Semidiurnal diurnal and mixed tides Semidiurnal Tide with 2 high and low points each tidal day Diurnal Tide with one high and low point each tidal day Mixed Tides Tide system where high tides regularly reach different heights and low tides regularly drop to different levels IV Relative influence of the Moon and the Sun The gravity of both the sun and the moon that cause ocean tides on Earth The moon s gravity is the most influential because it s much closer to Earth than the sun V Consequence of lunar declination diurnal inequality Lunar Declination causes the Diurnal Inequality Unequal highs and lows result Declination angle max 28 5 deg VI The lunar day why it is longer than the solar day The lunar day is 50 minutes longer than a solar day because the moon revolves around the Earth in the same direction that the Earth rotates around its axis So it takes the Earth an extra 50 minutes to catch up to the moon VII Springs and neaps in the lunar month phases of the Moon During each lunar month two sets of spring tides and two sets of neap tides occur The lunar month is the 29 53 days it takes to go from one new moon to the