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University of Toronto Scarborough
Environmental Science
Tanzina Moshin

EESA09H Lecture 1 Notes 1. Contact Information: Instructor: Tanzina Mohsin Room: SW648 Tel.: 416-287-7245 Email: [email protected] TAs: Kinson He Yin Leung Yukori Hori Jerry Jein 2. Marking Scheme Midterm: 30% Participation: 15% Final: 55% (Midterm, Final: Multiple Choice, T/F, Fill in the Blank, Matching, Definitions, Short Answer, concept maps) 3. List of Lectures (tentative) 1. Introduction to Wind 2.Global Wind Circulation 3. Hurricanes 4. Midlatitude Cyclones 5. Thunderstorms/Tornadoes 6. Polar lows Midterm (to be announced on the balckboard) 7. Thermal winds 8. Measuring Winds 9. Winds and Pollution 10. Wind Power 11. Climate Change: The role of Wind 12. Review Each week the PowerPoint presentation of the lecture will be posted on the course Web page. In addition a set of notes is being developed (this document, for example) which will expand on the lecture and provided additional references. READ THE COURSE OUTLINE FOR DETAIL INFO ON THE COURSE ELEMENTS. 4. Mythological and Cultural Winds Wind has played a key role in humanity’s mythology and cultural development. Mythological figures such as Aeolus (Greek god of Wind), Feng Po Po (Chinese goddess of wind), Haya-ji (Japanese god of wind, whirlwind), Nilch’i (Navajo holy wind) have played key roles in the world views in their respective cultures. In early Japanese culture, their civilization followed the Shinto, spiritual principles to maintain their connection between their ancestors and the living. Fujin was one of the earliest gods of Shinto, the god of wind. Wind is seen as a pure substance and considered a universal power, literally providing a spiritual connection between them. In the Hindu and Buddhist religions, wind is viewed as the nature or state of a god, referred to as “vayu”, “pavan” and “godai”. Wind is one of the five great elements respected, studied and celebrated by spiritualists from other religions such as Islam, Judaism, and Christianity in their quest for wisdom. Winds also play a metaphoric role in literature including movies. In stories such as Gone with the Wind (1939), Chocolat (2000), and The Wind that Shakes the Barley (2007) winds are a metaphor for change in a society or community. Storm imagery in The Hurricane (1999), Monsoon Wedding (2001), and Twister (1996) are reflected in the interpersonal dynamics within the movie. Of course sometimes a wind is a wind and is not metaphoric. There are a number of books that describe the physics of wind and its impacts. Wind by Jan DeBlieu and Windswept by Marq de Villiers are beautifully written books covering many physical and social elements of wind. 5. Outline of this lecture Atmospheric Primer: The history of wind - 4.6 billion years of air The Basics - composition - properties Current challenges 6. Atmospheric Primer: The history of Wind The earth’s atmosphere has existed for 4.6 billion years, since the earth was formed. The composition of the atmosphere has not been constant. Variations in atmospheric constituents have occurred due to three main controls: geological, biological and anthropogenic. Geologic Control The early earth’s atmosphere had a composition largely the result of volcanic emissions, carbon dioxide (CO ) and methane (CH ). About 3.8 billion years ago life 2 4 appeared. This early life, which was anaerobic (not needing oxygen) in nature flourished in this environment. It could be called the “Age of Bacteria”. After 2.3 billion years of the methane and carbon dioxide atmosphere, there was an abrupt change in atmospheric conditions. Biological Control 2.3 billion years ago oxygen made an appearance in the atmosphere and stabilized at 21%. Simultaneously, aerobic life (life needing oxygen) forms appeared and flourished. The atmosphere has been relatively constant since this time although there have been variations in trace gases such as carbon dioxide. These variations have played a key role in determining the thermal conditions of earth. The Gaia hypothesis was proposed by James Lovelock in the 1970s to explain the interaction of climate with biology. The basic premise is that life modifies the environment to best suit itself. For example, 21% oxygen is optimum for aerobic life. In contrast, Mars and Venus are in a static equilibrium with high levels of carbon dioxide and methane. One may ask why switch from anaerobic conditions to aerobic conditions 2.3 billion years ago? The early sun produced 30% less energy (Archean Era). Since then, the solar output has been gradually increasing. The early earth with high levels of methane and carbon dioxide had a strong greenhouse effect (see later in these notes for an explanation of the greenhouse effect). This led to conditions warm enough for life. After 2.3 billion year solar output increased and the earth was becoming too warm, the switch to aerobic life, reduced the greenhouse gases (CO , C2 ) an4 cooled the planet. We now have considerably lower levels of CO in the atmosphere than the 2 early earth. The Gaia hypothesis postulates that the atmospheric constituents have been controlled by life to optimize conditions for life. Anthropogenic Control During the Carboniferous Period (360 – 290 million years ago) during the Paleozoic Age life arrived on land. The sun’s energy was converted to plant material via the biological process photosynthesis. Photosynthesis is the process by which plants take carbon dioxide in the atmosphere to create plant material (long carbon chains). In conjunction with water (H O)2 oxygen (O ) is2stripped from the carbon dioxide molecule (CO ) 2nd released to the atmosphere. When a plant dies, the plant material rots in an oxidation process which returns the carbon back to the carbon dioxide form. However not all of the decaying plants are fully oxidized. This is the source material for coal and oil. Geologic pressure converts the plant material into these fossil fuels. These are stored for millions of years, often well below the earth’s surface. It represents a large reservoir of stored solar energy, essentially a biogeochemical battery. Many of today’s air quality problems arise from the rapid release of this stored energy (smog, acid rain, global warming). The story of coal is an important chapter in human history. It represents the first major anthropogenic modification of the atmosphere. Three countries play significant contributions to this. Britain experienced an industrial revolution in the early 19th century assisted by the easy accessibility of coal in Britain and the invention of the steam engine which allowed the more efficient mining of coal. This was followed by the industrialization of the northeastern United States in the 19th and 20th centuries. This industrialization has spread to most of the western world. An industrialization of China predates these two by several centuries. Coal was used to forge steel, mainly used to produce effective armaments, in China in the 11 century. China is now undergoing a second, much more massive industrialization at the end of the 20 th st century and beginning of the 21 century. The atmosphere appears to have become a modern dumping ground. Fossil fuels (coal, oil, and other hydrocarbons) are the major sources of emissions and are linked to Acid Rain, Urban Air Quality, Urban Heat Island and Global Warming. Other industrial emissions are linked to Ozone Hole. 7. The Basics Composition - What is air made of? - Clouds - Layers of the atmosphere - What is wind? Observing the Atmosphere - What do we measure? - How do we measure? Composition Matter can appear in three different phases: solid, liquid and gas. All three phases are represented in the atmosphere. Most prevalent is the gas phase. Liquid phase appears as clouds and the solid phase is referred to as particulate matter. The gas phase consists of gases that are permanent with fixed percentages and those that are variable in their concentration. Below is a table showing values of both the permanent and variable gases. The permanent gases are in dynamic equilibrium and not static equilibrium. This means that for each permanent gas, the balance is achieved by processes in the atmosphere that are balanced. For example, the 21% oxygen level is the result of both creation and destruction processes that are balanced to leave a constant level. (A static equilibrium is produced when there are no creation and destruction processes. This may be the case for Mars and Venus.) The variable gases
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