NR 150 1st Edition Exam 3 Study Guide Lectures 9 11 Lecture 9 March 26 What two factors drive the mass flow of ocean water Wind and gravity What is the difference between surface currents and thermohaline currents Surface currents are wind driven movements of water at or near the ocean s surface above the pycnocline Thermohaline currents are slow deep currents that affect the cast bulk of seawater beneath the pycnocline What does surface and thermohaline circulation affect Surface and thermohaline circulation affect temperature climate and biological productivity What are gyres Gyres are a circuit of mid latitude currents around the periphery of an ocean basin Gyres in balance between the pressure gradient and the Coriolis Effect are called geostrophic gyres What phenomena explains the net movement of water in surface currents The Ekman spiral which causes the layers of water to successively move at an angle to the right left of the overlying water The resulting phenomena is Ekman transport which causes the net motion of water to be 90 to the right left in the Northern Southern Hemisphere What are the names of the six great surface circuits North Atlantic gyre South Atlantic gyre North Pacific gyre South Pacific gyre Indian Ocean gyre Antartic Circumpolar Current not a gyre How many currents and what type of currents make up a gyre Four currents total make up a gyre There are two boundary currents an Eastern and Western and two transverse currents What differences would occur in gyres if the Coriolis Effect wasn t present Without the Coriolis Effect the ocean s gyres would be in perfect concentric shapes With the Coriolis Effect the shape is deflected and stretched in the direction of the winds What is Westward Intensification Westward Intensification is when western boundary currents are narrower warmer deeper faster and stronger currents with a steep slope Compares to Eastern boundary currents which are broad shallow cold and weak currents with gentle slopes What is usually found in the middle of gyres Why Large garbage and debris patches are typically found in the center of gyres due to the lack of water movement in those areas Lecture 10 March 21 What are some of the differences between circulation and waves Circulation transports mass via Ekman transport and geostrophic flow whereas waves are unable to transport mass only energy Circulation is also affected by the Coriolis Effect while waves are not Define a progressive wave and its components Progressive waves are waves which move forward They are composed of a wave crest which is the highest point of the wave and a wave trough which is the lowest point of the wave Other components include the period of the wave which is how long it takes for a crest to move from point A to point B and wavelength which is the horizontal distance between two crests How does the depth of the water influence the behavior of waves If a wave is in water deeper than half of its wavelength it is considered a deep water wave because too little wave energy is contained in the small circles orbits below that depth Only capillary and wind waves can qualify as deep water waves If a wave is in water shallower than 1 20 of its wavelength it is considered a shallow water wave and the orbits of water molecules are flattened as they approach shore What is the difference between capillary waves and wind waves Capillary waves form as wind friction stretches the water surface and as surface tension tries to restore it to smoothness Wind waves develop from capillary waves and are gravity waves formed by the transfer of wind energy into water What are the factors that influence wind wave development Swells are the smooth undulation of ocean water caused by wave dispersion Wind duration also influence wind wave development because winds that blow for a short time will not generate large waves Wind strength also influences wave development because wind must be moving faster than the wave crest for energy transfer to continue Another factor that influences wave development is fetch which is the uninterrupted distance over which the wind blows without a significant change in direction A fully developed sea also influences wind wave development because it is the maximum wave size possible for a wind of specific strength duration and fetch When are wave heights the highest Wave heights are the highest when there is no interference from continents How do interferences produce irregular wave motions Destructive interference is when two waves meet and cancel each other out Constructive interference is an additive interference that results in waves larger than the original waves Rogue waves are when interference results in a wave crest higher than the theoretical maximum Name and explain the different kinds of waves Deep water waves become shallow water waves as they approach the shore Internal waves are subsurface waves that form between water layers of differing densities Standing waves like seiches oscillate vertically with no forward movement and rock back and forth at a specific resonant frequency in a confined area Storm surges are abrupt bulges of water driven on shore by a tropical cyclone hurricane or a frontal storm Under what conditions does a wave refract Waves refract when they approach the shore at an angle Lecture 11 April 7 What are some of the differences between deep water waves and shallow water waves Deep water waves occur when the water depth is more than half the wavelength Shallowwater waves occur when the water depth is less than 1 20 of the wavelength The speed of deep water waves can be determined by dividing the wavelength by the period of the wave The speed of shallow water waves can be determined by taking square root of the product of the acceleration due to gravity and the depth of the water What is a tsunami How are they caused A tsunami is a long wavelength shallow water progressive wave caused by the rapid displacement of ocean water Tsunamis that are caused by the sudden movement of faults are correctly called seismic sea wave They can also be caused by landslides icebergs falling from glaciers volcanic eruptions asteroid impacts and other direct displacements of ocean water What are some differences between tsunamis and tides Tsunamis are shallow water free waves that are triggered by seismic events and other events that displace water Tides are also shallow water forced waves that are the result of the gravitational forces from the