Rowan Moreno

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Environmental Science
Tanzina Mohsin

Final Exam: an overview of the course Lecture 1: 1. What are the characteristics of the Greek Gods of Wind?  Greeks (Euro-centric)  Aeoulus is designated by Zeus to look after the four winds o Zephyrus – gentle, west wind o Boreas – chilly, north wind o Notos – southern rain bringer o Eurus – ill-tempered east breeze 2. How the natural environment was dominated by geologic, then anthropogenic control?  Geologic Control o Early earth  Atmospheric composition largely the results of volcanic emissions (geologic control) – CO and CH 2 4  Life appeared 3.8B years ago o 2.3B years of methane, carbon dioxide in the atmosphere  Aerobic conditions, Age of Bacteria o Abrupt change 2.3B years ago  Oxygen makes an appearance in the atmosphere and stabilizes at 21%  Aerobic life forms appear and flourish (“biologic control)  Links to Gaia hypothesis (James Lovelock)  Biologic Control o Basic premise is that life modifies the environment to best suit itself o 21% O is2optimum for life o Mars and venus are in a static equilibrium with high levels of CO 2nd CH 4  Anthropogenic control o During the Carboniferous period (360-390M years ago) during the Paleozoic Age, life arrives on lands  Sun’s energy converted to plant material (photosynthesis)  Decaying plants are not fully oxidized  Converted to coal and oil under geologic pressure  Stored for millions of years  Many of today’s air quality problems arise from the release of this stored energy o Coal  First major anthropogenic modification of the atmosphere  Britain – Industrial Revolution – 19 Century  US – 19 and 20 Centuries th  China 11 century, present 3. Why switch from anaerobic conditions to aerobic conditions 2.3B years ago?  Gaia Hypothesis oEarly sun produce 30% less energy (Arhcean) oSolar output has been gradually increasing oEarly earth with high levels of methane and carbon dioxide had a strong GH effect which led to conditions warm enough for life oAfter 2.3B years, solar output increased and earth was becoming too warm, the switch to aerobic life, reduced the GH gases, and cooled the planet oWe now have considerably lower levels of CO in t2e atmosphere than the early earth oGaia hypothesis postulates that the atmospheric constituents have been controlled by life to optimize conditions for life 4. Vertical Structure of the Atmosphere  Explain the temperature change within the layers in the atmosphere oThe troposphere extends to approximately 11 km, varying from 13 km at the equator and 8 km at poles. The layer is well mixed vertically. Virtually all weather occurs in this part of the atmosphere. 75% of the mass of the atmosphere is in the troposphere. The tropopause is the isothermal region separating troposphere and stratosphere. Warming occurs at the surface from the sun's radiation. Temperature decreases in the troposphere (on average) by 6.5 oC per km. o The stratosphere extends from approximately 11 km to 50 km. Temperature increases with height in this layer. This warming is due to the conversion of incoming solar radiation into kinetic energy of motion via a layer of ozone. This process is described in detail in lecture 4 and relates to the ozone hole issue. This layer is very stable (very little vertical mixing). o The mesosphere extends from 50 to 85 km. Temperature decreases with height in this layer. It is a well mixed layer and is less stable than stratosphere. o The thermosphere extends above 85 km. In this layer temperature increases with height. Incoming solar radiation is absorbed by molecular oxygen and energy is converted to the kinetic energy of motion. Although the temperature is depicted as being very warm, one would not feel warm at that level of the atmosphere. This is because the air has very low density at this height and thus there is a low transference of heat which makes us feel warm. Lecture 2: Concep
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