NaimExplain

How does sediment accumulation affect the bathymetry of a spreading center? Where are the affects more pronounced? Answer: Sediment accumulation will smooth out the bathymetric features and it is more pronounced with greater distance from the spreading center because there has been a longer amount of time for sediments to accumulate.

What is occurring at hydrothermal events in terms of water exchange? Answer: Cold ocean water is seeping through fissures in the crust. When the water comes close to the magma chamber, it is warmed, then rises and boils out of the fissures near the center of the rift zone

What is the continental rise? Where is it found? Answer: It is formed by the accumulation of sediments at the base of the continental slope and only occurs as passive margins

What are the characteristics of a passive margin? Give an example. Answer: There is little earthquake activity. Faces a divergent plate boundary. Has a broad continental shelf. The Atlantic Ocean

What are the characteristics of an active Margin? Give an example Answer: There is earthquake and volcanic activity. Faces a convergent boundary. Narrow continental shelf. Pacific

Why does the continental shelf in the Gulf of Mexico have numerous pits or pockmarks? Answer: The Mississippi river and other rivers have deposited large amounts of sediment on the shelf. The weight of the sediments causes salt domes to rise and spread out, the dissolve and collapse. causing the pits

What is important about the pockmarks and pits of the Gulf of Mexicos continental shelf? Answer: They cause oil and gas deposits to rise towards the surface and be more accessible.

How are submarine canyons aligned with the continental shelf and how are they formed Answer: They are aligned at right angles with the shelf and they are formed by turbidity currents

What physical property of water can sound be used to measure? Answer: Temperature

What is the photic zone? How deep is it in coastal waters versus the open ocean? Answer: The photic zone is the upper layer of the ocean that is well-lit and where most primary production occurs. It is approximately 40 m deep in coastal waters and 100m deep in the open ocean

What wavelength (color) of light penetrates deepest in the ocean? Which is attenuated most rapidly in the surface? Answer: Blue light penetrates deepest, red light is absorbed at the shallowest depths

What is the speed of sound in the surface ocean? Why does the speed decrease with increasing depth to a certain point? Answer: 1500 meters per second. The speed decreases with depth as the temperature of the water decreases. (NOTE: at a certain point, increasing pressure causes the sound speed to increase again)

What are three things that can happen to light as it enters water? Answer: It can be refracted, absorbed, or scattered

Compare the speed and distance that sound travels in the ocean versus air Answer: Sound travels faster and farther in the ocean than in air

Why is light refracted when it enters water from air? Answer: There is a change in density, the water is more dense than the air and the light travels more slowly and is refracted

San Franciso and Norfolk are both cities on the coast. Why does Norfolk have much greater temperature fluctuations through the seasons? Answer: The prevailing winds are to the East and so the air the flows over Norfolk is influenced by land temperatures while the air the flows over San Francisco is moderated in temperature by flowing over the ocean which experiences fewer temperature fluctuations over the seasons in comparison to land

In what regions of the Earth do SURFACE ocean temperatures fluctuate the most over the year? Answer: temperate regions

Why are the SURFACE ocean waters in the tropics less salty than in temperate regions? Answer: Precipitation greatly exceed evaporation and this leads to fresher surface waters

What is the pycnocline? The thermocline? The halocline? Answer: Pycnocline-the zone where density increases rapidly with depth. Thermocline--zone where temperature changes (usually decreases) rapidly with depth. Halocline--zone where salinity changes (usually increases) rapidly with depth

How do seasonal changes in sea ice cover provide a global thermal buffer? Answer: As ice changes state from solid to liquid, large amounts of heat are required to undergo the latent heat of fusion during which there is no temperature change. The Earth can absorb large amounts of heat and experience no change in temperature because the heat is 'used' to convert ice to liquid water (the reverse process buffers against large drops in temperature as the Earth loses heat)

What controls the vertical stratification of the oceans? Answer: density

How does the vertical profile of temperature in polar regions differ from the profiles in tropical and temperature regions? Answer: The temperature is low and changes very little between the surface and the deep waters

How does salinity affect the freezing point of seawater? Answer: Salinity lowers the freezing point, the higher the salinity, the lower the freezing point

What is heat capacity? Does water have a high or low heat capacity? What does that mean? Answer: The measure of heat required to raise the temperature of 1 gram of a substance by 1 degree C. Water has a high heat capacity. That means it takes a large gain or loss of heat for water to change it's temperature

What is a polar molecule? What makes the water molecule polar? Answer: a molecule with opposing charges; it has a positive end and a negative end

If you add 90 calories of heat to 1 gram of liquid water that is at 0 degrees C, what will it's new temperature be? Answer: 90 degrees C

What is a covalent bond? Where is this bond found in a water molecule? Answer: Covalent bonds hold two atoms together by sharing electrons. In the water molecule, covalent bonds hold the oxygen and hydrogen atoms together

What is sensible heat loss or gain? Answer: A measurable decrease or increase in heat--there is a change in temperature

Why is ice less dense than liquid water? Answer: The hydrogen bonds between the water molecules force the molecules to form a lattice structure when water freezes and fewer water molecules can fit into the same space, making ice less dense

What is the latent heat of fusion or vaporization? Answer: Changes in heat (gain or loss), but no change in temperature

What are two major factors forecasters look at to predict tropical cyclone formation and strength and how do these factors act to aid in the formation of these storms? Answer: Sea surface temperature is important to the formation and strength of tropical cyclones as the warmer the water, the greater the energy source for the storm. Atmospheric dust is also important as it acts as a nuclei for water droplet formation and thus accelerates the release of the latent heat of vaporization

Why do tropical cyclones weaken as they move over land? Answer: They encounter the friction of moving over land and they lose the energy from the latent heat of vaporization without access to warm surface water

Geographically on the globe, where do most tropical cyclones form? Why? Answer: Near the equator because this is where there are consistently high sea surface temperatures

What provides the energy for a tropical cyclone? Answer: The latent heat of vaporization of water

Do tropical cyclones form between air masses or within one air mass? Which direction do they rotate in each hemisphere? Answer: Tropical cyclones form within one warm, humid air mass. They rotate counterclockwise in the NH and clockwise in the SH

In the example of the tropical cyclone that is moving to the northeast, on which side of the storm will there be the greatest destruction from wind? Answer: To the East of the storms eye because this is where there are the highest winds. The winds are on the western side of the storm are slowed down by the forward movement of the storm, but those on the Eastern side are not impeded in this way

Where and how do extratropical cyclones form? Answer: They form at the Polar front (between the polar and Ferrel cells) and they form when the air masses of different density moving past each other twist (Counter clockwise in the NH and Clockwise in the SH)

What is a front? When do we define a front as being a cold front or a warm front? Answer: A front is a boundary between air masses of different density. It is a cold front if the cold air is lifting the warm air mass and it is called a warm front if the warm air does the lifting

Where are monsoon winds found? Briefly describe the air circulation and resulting climate conditions in both winter and summer Answer: Monsoon winds are found in Asia, primarily over India and Southeast Asia. In winter, the land cools more than the ocean and this cool air sinks and moves toward the ocean, resulting in dry conditions. In summer, the land heats more than the ocean and as this warmer air rises, the cooler, moister air from over the ocean moves over the land resulting in wet rainy conditions.

Describe how sea breezes and land breezes occur over a 24 hour cycle Answer: high heat capacity drives this: during the day, the sun warms the land faster than the sea, so that air rises, but the cooler air over the ocean descends and flows offshore, creating a seabreeze. at night, the land cools faster than the ocean, making the air fall and flow offshore, where the air is heated by the ocean and it rises.

What is low atmospheric pressure associated with? High atmospheric pressure? Answer: Low pressure is associated with air rising and high pressure is associated with air sinking

Where are the Polar fronts located? Briefly describe the atmospheric circulation here and the resulting climate conditions. Answer: The Polar fronts are located at 60 degrees N and S, at the convergence of the Ferrel and Polar Cells. Air is rising here resulting in a stormy, cloudy climate and relatively high precipitation year-round

What atmospheric circulation cell are the Westerlies associated with? What latitude range do they occur in? What is the direction of prevailing winds in each hemisphere? Answer: Westerlies are associated with Ferrel cells and located between 30 and 60 degrees N and S. The winds blow from the Southwest in the Northern hemisphere and from the Northwest in the Southern hemisphere.

What is the Intertropical Convergence Zone? Why does it experience a greater change in its North-South position over Asia than over the Pacific Ocean? Answer: The area around the equator where the Hadley cells meet. It is characterized by low wind activity. It's seasonal NS position changes more over Asia because there is more land surface and less ocean surface and so there is less of a buffering effect from seasonal temperature changes because there is less buffering due to the heat capacity of water.

Where are the 'horse latitudes', or subtropical highs? Briefly describe the atmospheric circulation here and the resulting climatic effects. Answer: The 'horse latitudes' are located at 30 degrees N and S, where the Hadley and Ferrel cells meet. Air is sinking here and since that air has lost most of it's precipitation, these ares are often dry resulting in desserts like the Sahara (and also higher ocean surface salinity because there is more evaporation than precipitation!)

Where are the trade winds located and what is their prevailing wind direction in each hemisphere? Answer: The Trade winds are located between the equator and 30 degrees N and S. The prevailing direction is to the Northeast in the Northern hemisphere and to the Southeast in the Southern hemisphere

How many major circulation cells are there on the Earth? Answer: 6, 2 Hadley cells near the equator, 2 Ferrel cells in the temperature latitudes, and 2 polar cells

Describe the circulation of a Hadley cell. What causes the air to circulate and move in the direction that it does? How does it move in the Northern and Southern hemisphere? Answer: The energy of the sun causes the heating that causes air to rise and drives the circulation. In a Hadley cell, the air rises and moves towards the poles, as the air cools and falls back toward the equator, air is deflected to the right in the northern hemisphere and the left in the southern hemisphere

In which direction does the Earth rotate? If you don't remember, you can figure it out by thinking about time zones in the US, where does night happen first. Answer: The Earth rotates to the East

What two major factors determine the amount of heat reaching the Earth's surface? Answer: latitude and season

What is the energy source that drives atmospheric circulation? Answer: heat from the sun

What are the three main gases that make up the atmosphere and their percent composition? Answer: 78% Nitrogen, 20% oxygen, 1 % other

In a simplified circulation cell, describe how air is moving from the equator, to the poles, and back and what is driving that circulation. Answer: Air at the equator is heated by energy from the sun and rises, it moves towards the poles where it is cooled, sinks, and flows along the surface of the Earth back towards the equator

Why are there seasons at the temperate and polar latitudes? (why is the solar energy reaching the Earth in these areas not the same throughout the year?) Answer: The Earth is tilted on it's axis and so as it orbits around the sun, the temperate and polar latitudes are exposed to varying amounts of solar energy which dictates the different seasons

Why do high and low tides change by 50 minutes each day? Answer: Tides follow the lunar day, which is longer than a solar day, it is 24 hours and 50 minutes

What does the equilibrium theory of tides assume? Answer: The seafloor does not influence tides and there are no interfering continents

What does the dynamic theory of tides take into account? Answer: That tides are waves and so have certain behaviors in shallow water and that continental also have an effect

How does the gravitational pull of the moon in combination with the Earth's motion affect the oceans on Earth? Answer: It creates a bulge in the oceans in the direction of the moon and on the opposite side of the Earth

What is an amphidromic point? Answer: A point of no tidal motion which a tidal crest rotates around

What are the three different flow phases of a tide in and out of an enclosed area like a river mouth? Answer: Flood current--water rushing in, Ebb current--water rushing out, and slack water--a time of no currents

How has tidal friction affected the Earth over time? Answer: It has slowed the rotation of the Earth from 22 hours/day to 24 hours/day

If the bulge in the oceans remains stationary over 24 hours, what causes high and low tide to occur at a fixed point on the Earth? Answer: The Earth is rotating under the bulges so a fixed point on the Earth is moving from being under a bulge (high tide) to away from the bulge (low tide)

What are the three basic types of tides? Give a brief description of each. Answer: Diurnal tides, one high and one low tide every 24 hours. Semidiurnal tides, two high and two low tides every 24 hours of equal magnitude. Mixed tide, two high tides and two low tides every 24 hours of differing magnitude

Where are some of the largest waves in the world found? Answer: In the Southern Ocean

What is interference? What are the possible outcomes? Answer: Interference occurs when two wave trains interact. The waves can either cancel each other out (destructive interference) or add together to create even larger waves (constructive interference)

What is a standing wave? How is it created? Answer: A standing wave is a wave that oscillates around a single node--the wave has crests and troughs in a fixed position. This occurs when a wave strikes an obstacle directly and the reflected waves interfere with the oncoming waves

What causes waves approaching shore at an angle to refract? Answer: The portion of the wave in shallow water (less than L/20), encounter the friction of the bottom and slow down, while the rest of the wave in deep water continues at its original speed, this causes the wave to bend or refract

What is a seiche? What causes it (disturbing force was discussed in a previous lecture segment)? Answer: A seiche occurs when water sloshes back and forth in a closed basin, like a lake. It occurs due to changes in atmospheric pressure (most common), storm surge, or a tsunami

When does a deep-water wave become a shallow-water wave? Answer: When it is in water where the depth is less than 1/20th of its wavelength

In a wave train, what happens as the leading waves are drained of energy and disappear? Answer: New waves are created at the end of the wave train

What is the simple equation that relates wavelength (L), wave period (T), and the speed (c) of a deep-water wave? Answer: c=(L/T)

What is dispersion? Why does it happen? Answer: Dispersion is the process of wave separation by size (wavelength). This happens because waves with greater wavelengths move faster--the speed of the waves are controlled by their wavelength

As deep-water waves become shallow-water saves, how does their period, speed, and wavelength change? Answer: The period stays the same but the speed and wavelength decrease

How does the speed, wavelength, and wave height of deep-water waves change over long distances? Answer: The speed, wavelength, and wave height of cep-water waves remain relatively constant over long distances

What significant thing happens at a depth of approximately 1/2 the wavelength? Answer: The orbital path of water particles is essentially negligible. This is the depth where wave motion generated at the surface is no longer occurring

Besides tides, what type of wave accounts for most of the energy in the surface ocean? What are its disturbing and restoring forces? Answer: Wind waves. Disturbing force is wind an the restoring force is gravity

What type of wave has the smalls wavelength? What are its disturbing and restoring forces? Answer: Capillary waves. Disturbing force is wind and restoring force is the cohesion of water molecules

What type of wave has the longest wavelength? What are its disturbing and restoring forces? Answer: Tides. Disturbing force is the gravitational attraction of the moon and sun and the rotation of the Earth. The restoring force is gravity

What is a disturbing force? A restoring force? Answer: A disturbing force is an energy force that causes waves. A restoring force is an energy source that returns the water surface to flatness after a wave has passed

How do El Nino conditions affect fisheries production? Why? Answer: Fisheries production is reduced during El Nino conditions because the lack of high nutrient water in the absence of upwelling means that plankton production is also low and because plankton are the base of the food chain, this results in lower fish production

What are the changes in ocean circulation that occur during an El Nino? Answer: The flow of water from the East to the West is decreased as the trade winds weaken and the pool of warm water in the west flows to the east as there is now not enough force to keep the thermocline tilted. The typical upwelling conditions off South America are changed to downwelling conditions

What changes in atmospheric circulation cause El Nino? Answer: There is a change in position of the low and high pressure areas in the Pacific with the Low pressure area in the Western Pacific moving to the central Pacific and a high pressure area developing the Western Pacific. This causes a weakening of the trade winds and a reversal in their flow in the Western Pacific

What are the effects of an El Nino event? Answer: Low productivity and higher sea surface temperatures in the Eastern Pacific (also higher sea level and greater and more intense storms in the Eastern Pacific)

What drives the global thermohaline circulation? Answer: Water at the poles is cooled and it's salinity increases due to the exclusion of salt as seawater freezes making it dense and it sinks (down wells)

What causes coastal upwelling off the Oregon coast? Answer: Prevailing winds are from the north and the Coriolis force deflects water to the right, away from the coast. This induces water from below to be upwelled to fill the space along the coast.

Under what conditions does Langmuir circulation occur? What part of the water column does it affect? What does it do to floating particles? Answer: Langmuir circulation occurs when there are steady winds in one direction. It occurs in the upper 20 m of the water column. The opposing vortices concentrate floating particles in lines between them and creates surface slicks or concentrations of these particles

How will rising global temperatures affect the ocean conveyor? What major climate affect will this initially have? Answer: The North Atlantic will get fresher as more Arctic ice melts and this will prevent downwelling. Europe will get colder as the Gulf stream will circulate back towards the equator sooner

What is one of the larges and strongest upwelling zones on the Earth? What drives the upwelling here? Answer: The area around the equator. The Southeast trade winds blow along the equator and the Coriolis force deflects water to the right North of the equator and to the left south of the equator. This causes the surface waters to essential part a the equator and induces water from below to be upwelled to fill the space

Why are upwelling zones often highly productive areas? Answer: The water that is upwelled is generally rich in nutrients

What are the characteristics of a Western boundary current? Name an example Answer: Narrow, fast, deep currents on the western side of a geostrophic gyre that carry warm water towards the poles. They transport large amounts of water and are nutrient poor. Examples are the Gulf Stream, Kurishio, Brazin, Agulhas, and East Australian currents

What is a warm core ring? Answer: An eddy, a spinning parcel of water that has pinched off a meandering current and has a core of warm water in the center

What is the overall direction of net transport in an Ekman spiral in the Southern hemisphere? Answer: it is 90 degrees to the left of the prevailing wind direction

What is a Sverdrup equivalent to in terms of water flow? Answer: 1 million cubic meters of water per second

What are transverse currents? What drives their flow? Give an example Answer: Transverse currents link Eastern and Western boundary currents. They are driven primarily but the Trade winds and the Westerlies. Examples are the North and South Equatorial currents, the North Pacific, North Atlantic, and Antarctic Circumpolar currents

What is Westward intensification and what causes it? Answer: Currents flowing from West to East at higher latitudes (in either hemisphere!) have water deflected more quickly and strongly towards the center of the gyre than currents flowing form high latitudes towards the equator because the Coriolis force is greater near the poles. This leads to an asymmetrical gyre and explains why western boundary currents are fast and deep while easter boundary currents are the opposite

Why does a dome of water form in the center of a gyre? Answer: ekman transport forms a pressure gradient

What are surface currents? Answer: Wind driven movement of water at the surface, primarily in the upper 400 m of water above the pycnocline

What are thermohaline currents? Answer: Slow, deep currents (below the pycnocline) driven by the density of water masses

How does the Coriolis force affect the movement of surface currents in each hemisphere? Be specific about the angle. Answer: The coriolis force deflects water at a 45 degree angle from the prevailing wind direction--to the right in the Northern hemisphere and to the left in the Southern hemisphere

What forces are responsible for the flow of water from east to west along the southern edge of the North Atlantic gyre? Answer: The pressure gradient set up by the domed water in the center of the gyre forces the water to flow away from the dome toward the south and the Coriolis force deflects the water to the right