NR 150 1st EditionExam # 2 Study Guide Lectures: 5-8Lecture 5 (February 19)What is bathymetry?Bathymetry is the study of ocean floor contours.What are the different methods of conducting bathymetry? How accurate are they? What kind of imagery does this method create?Single beam systems, called echo sounding, are not always accurate since the speed of sound through seawater varies with temperature, pressure and salinity. It creates 2D imagery. Multi-beam systems can have as many as 121 beams radiating to the seafloor and is much more accurate and efficient. It creates 3D imagery. Satellite altimetry is used to measure the sea surface height using radar pulses. This is relatively accurate but it focuses on the variations of elevation in the surface water rather than depth and is used to map out certain features in the seafloor (like mounts).What are the different kinds of continental margins?There are passive margins, which are margins facing the edges of diverging plates that have littleearthquake or volcanic activity associated with them.There are also active margins, which are margins near the edges of converging plates or near places where plates are slipping past each other that are characterized by volcanic activity.Which kind of continental margins surround the Atlantic Ocean? The Pacific Ocean?Passive continental margins. Active continental margins.What is the continental shelf?The continental shelf is the transition between the continental shelf and the deep-ocean floor. It’s where sediments from erosion on land build up and it gently slopes seaward. It is shaped by the movement of tectonics, ocean currents, and the relative sea level (low vs. high).What is the continental slope? What is the continental rise?The continental slope is the transition between the continental shelf and the deep-ocean floor. The sediments on the continental slope mainly come from the shelf. The continental slope is also steeper than the continental shelf, but slopes on the active margins are generally steeper than passive margins. The bottom of the slope signifies the true end of the continent. The continental rise is the sediments that accumulates on the bottom of the continental slope.What is the shelf break?The shelf break is the abrupt transition from the continental shelf to the continental slope. The shelf break is essentially constant in depth (about 140m) world-wide.Where do submarine canyons typically form? What are turbidity currents?Submarine canyons typically form at the junction between continental shelf and the continental slope, where they often terminate on the deep-sea floor in a fan-shaped wedge of sediment.What are the kinds of major features that cover the deep-ocean floor?Oceanic ridges are mountainous chains of young, basaltic rock at an active spreading center of an ocean. Hydrothermal vents are hot springs on active oceanic ridges where superheated water containing dissolved minerals and gasses escapes through vents. Abyssal plains are flat, cold, sediment-covered portions of the ocean-floor between the continental rise and theoceanic ridge. Abyssal hills are small, sediment-covered extinct volcanoes or rock intrusions associated with seafloor spreading. Seamounts are volcanic mountains that rise from the ocean floor and never grow tall enough to come close to the sea surface. Guyots are flat-topped seamounts eroded by wave action. Trenches are arc-shaped depressions in the deep-ocean floor.Lecture 6 (February 24) What is the hydrologic cycle powered by? What are the different reservoirs in the hydrologic cycle?The hydrologic cycle is powered by solar radiation and is sometimes assisted by geothermal energy. About 80% of precipitation falls back into the ocean so the world’s largest reservoir is the ocean. Most of Earth’s freshwater is frozen. Most unfrozen fresh water is ground water, not surface water. Most surface freshwater is in lakes and streams.What are some of the unique properties of a water molecule?Water molecules are polar and are held together by hydrogen bonds. The capability of forming hydrogen bonds with one another give water its high surface tension. It also allows water molecules to stick together (cohesion) and to stick to other materials (adhesion). As a polar molecule, water also acts as a powerful solvent.What is does it mean when a substance has a high heat capacity?Heat capacity is the amount of heat required to raise the temperature of 1 gram of a substance 1°C. High heat capacities mean the substance resists changing temperatures when heat is addedor removed.What is salinity? What is the principle of constant proportions?Salinity is the total quantity (concentration) of dissolved inorganic solids in water. The principle of constant proportions states the there is a constant ratio of various salts in seawater from many different locations.What is happening to the ocean’s acidity?The ocean is typically more basic than pure water. As carbon dioxide uptake of the ocean increases, the ocean is becoming more acidic because the carbon dioxide is contributing to the formation of carbonic acid.What is the ocean stratified by? What are these different zones?The ocean is stratified by density, and the zones of the ocean vary by temperature and salinity. The pycnocline isolates surface water from the denser layer below, and its density increases with decreasing depth. The thermocline is the middle zone in which temperature changes rapidly with depth. The falling temperature of the thermocline is a major contributor to the formation of the pycnocline. The halocline is a zone of rapid salinity increase with depth and it often coincides with the thermocline, creating a pycnocline.What are the different zones of the ocean according to the travel of light?The photic zone is the thin film of the lighted water at the top of the ocean which rarely extendsdeeper than 200m. The aphotic zone is the dark ocean below the depth to which light can penetrate.What are the properties of sound travel in the ocean?Sound travels faster in seawater than in air. It is usually the slowest at depths of about 1000m but fastest at shallow or deep depths. Refraction of sound waves cause shadow zones when paths of sound are bent.Lecture 7 (February 26)What is the difference between weather and climate?Weather is the state of the atmosphere at a specific time, whereas climate is the long-term statistical sum of weather in an area.What are the major components of the