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EESA09H3 Lecture Notes - Water Vapor

Environmental Science
Course Code
Tanzina Mohsin

of 8
Lecture 1 Notes
1. Contact Information:
Instructor: Tanzina Mohsin
Room: SW648
Tel.: 416-287-7245
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.
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 (CO2) and methane (CH4). About 3.8 billion years ago life
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
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 (CO2, CH4) and cooled the
planet. We now have considerably lower levels of CO2 in the atmosphere than the
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 (H2O), oxygen (O2) is stripped from the carbon
dioxide molecule (CO2) and 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