ENVS 101 1st Edition Lecture 17 Outline of Last Lecture I. Ocean Basins and Ocean WaterII. Ocean CirculationOutline of Current Lecture II. Ocean CirculationIII. Ocean Tides and WavesIV. Where Land and Ocean MeetV. Changing Sea LevelsVI. The Habitable Planet/Composition and Structure of our AtmosphereCurrent LectureDeep ocean circulation is the result of the sinking of dense, cold, saline surface water which propels a global thermohaline circulation system.- North Atlantic Deep Water (NADW), which starts around Iceland, sinks and spreads southwards.- Flowing beneath this water is the colder, more dense Antarctic Bottom Water (AABW)- These are parts of a larger global ocean “conveyor”Ocean tides: Tides consist of rhythmic, twice-daily rising and falling of ocean water along coastlines. This is caused by gravitational attraction between the Earth and the Moon, and to a lesser extent, the Sun.- Generates tidal bulges that are due to gravitational pull and inertial force. - The highest and lowest tides occur when the sun and moon are aligned (spring tides)- Least tidal range when sun and moon are not aligned (Neap tides)Reefs: Warm-water coastlines that are characterized by limestone reefs. These are typically colonies built by corals and other organisms, and have intense biologic productivity as well as diversity. There are three main reef types: Fringing reef: attached to /closely bordering land, Barrier reef: separated from land by a lagoon, and Atoll: roughly circular reef enclosing a lagoonthat forms when a volcanic island subsides.There are also Estuaries: semienclosed marine embayment diluted with fresh water entering by one or more streams. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Coastlines are classic examples of systems in a state of dynamic equilibrium. Coastal erosion tends to have significant impacts on human interests. There are various responses to coastal erosion, in three main categories: Hard stabilization, soft stabilization, and retreat.Ocean Waves: Surface waves receive their energy from wind. The size of a wave is determined by wind speed, duration, and fetch (distance). Wave height (from crest to trough) and wavelength (from crest to crest/ crest to trough) are also factors to consider. As waves move, every parcel of water revolves in a loop.As depth decreases, the wave’s shape is distorted; height increases, wavelength shortens, and the wave front grows steeper, eventually collapsing (breaking)Submergence: the rise of water level relative to the land. Emergence is a lowering of water levelrelative to the land. Cycles of emergence and submergence: related to the buildup and decay ofvast ice-age glacier systems.Changing sea levels: Sea Ice, land ice, and sea levelsWith all of the water that is locked up in the cryosphere, it is estimated that global sea level would be 65 to 80m higher if the ice sheets were to melt. The melting of the West Antarctic ice sheet alone could contribute about 8 meters to the sea level rise.Ocean Waves: Approaching shore, waves will become refracted to parallel the bottom contours.The path of an incoming wave can be resolved in two directional components. Parallel to the shore: longshore current, and Perpendicular to the shore: surf.Week 10 Section (Lecture of 3/27) : The Atmosphere- Through volcanic outgassing, abundant volatiles were released to surface, forming the Earth’s secondary atmosphere.- Unlike today’s atmosphere, this would have been composed of water vapor, methane, hydrogen, nitrogen, carbon dioxide and argon.- Earth had virtually no oxygen in its atmosphere- Almost all the free oxygen originated through photosynthesis. And the atmospheric compounds that formed with a combination of other elements oxygenated the atmosphere around 2.5 to 1.8 billion years ago.Initial oxygen reacted: with iron and other elements to form banded iron formation (important Fe resource).The Habitable Planet: With the buildup of molecular oxygen came an eventual increase in ozone. The ozone absorbs harmful UV radiation, and the ozone made it possible for life to flourish in shallow water and finally on land.Once the ozone was well established, the Cambrian Explosion occurred around 542 million years ago, and brought about the diversification of life on Earth. Oxygen levels have fluctuated over the past 200 million years from levels at 10% to as much as 25%.Another major chemical change in the atmosphere was the removal of carbon dioxide by sinking it into limestone and organic sediment.Composition and Structure of our Atmosphere: The air of our present day atmosphere varies due to the presence of Aerosols: tiny suspended liquid or solid particles.Water vapor: humidity from evaporation. - Nitrogen, oxygen and argon represent over 99% of the “dry” gases. Other important gases include: Carbon dioxide, methane, ozone and NOxTwo things energize the atmosphere: The Sun’s energy, which warms the atmosphere. Energy source for clouds, rain, snowstorms, wind, and weather. Another thing that energizes the Earth’s atmosphere is the Earth’s rotation: the axial tilt is responsible for seasons.There are 4 thermal layers of the Atmosphere, separated by pauses:- Troposphere: temperature decreases with altitude, most of our weather occurs here.- Stratosphere: temperature increases with altitude because of the presence of the ozone. - Mesosphere: temperature decreases with altitude, and this is also the coldest layer of the atmosphere.- Thermosphere: temperature increases with altitude, reaches the highest temperatures, and hosts the ionosphere (where auroras, or Northern Lights natural phenomena occur).- Oxygen molecules O, O2, and O3 absorb hazardous UV radiation from the SunAir pressure is the force exerted by the weight of the overlying air. It is measured with a barometer, and can indicate changes in weather. Air pressure decreases with altitude. Weather balloons carry radiosondes, weather instrument packages to measure conditions higher up in the