Class Notes (905,604)
CA (538,462)
UTSC (32,636)
EESA07H3 (45)
Lecture

Lecture 4

4 Pages
82 Views

Department
Environmental Science
Course Code
EESA07H3
Professor
Tanzina Mohsin

This preview shows page 1. Sign up to view the full 4 pages of the document.
Lecture 4: Atmosphere-Climate System
Composition and Structure of the Atmosphere
The very early atmosphere probably consisted of gases, mainly hydrogen and helium, which was
abundant in the solar system
Then came the geologic control
oUnder geologic control, a secondary atmosphere was formed:
Out gassing from cooling magma
Emissions from volcanoes
oEssentially no atmospheric O2, and highly corrosive
oHighly energetic-lightning, volcanic activity, high UV radiation
Then the biological control
oAnaerobic conditionsAge of Bacteria”
oAnaerobic bacteria developed about 3.5 to 4 bya
oCould survive in absence of oxygen and began the slow conversion of CO2 to O2
Gaia Hypothesis
oJames Lovelock, not about environmental control, life modifies the environment to best suit itself
oAtmospheric constituents have been controlled by life to optimize conditions for life
oAbrupt change occurred 2.3 bya, Os started to appear
oAs O2 started to become abundant, some was broken down by the suns radiation into atomic O2
and eventually formed ozone O3
oLife started to appear
oEvolution of the Atmosphere
Once rocks at surface were sufficiently oxidized, more oxygen could remain free in
atmosphere
There was switch from anaerobic to aerobic condition 2.3 bya
2.3 bya solar output increased and earth was becoming too warm, the switch to aerobic
life, reduce the greenhouse gases and cooled the planet
Now have lower levels of CO2 in atmosphere than early earth
O2 stabilizes at 21%, which is optimal for life on earth
Then came the Anthropogenic control
oDuring Carboniferous Period (290-360mya) life appears on land
Suns energy converted to plant material (photosynthesis)
Decaying plants not fully oxidized
Converted to coal and oil under geologic pressure, stored for millions of years
We used these fossil fuel for our comfort
oComposition now
Atmosphere currently consists of water vapour, aerosols (gaseous suspensions of find
solid or liquid particles)
Water vapour- less than 0.0001% of all the water on earth
Aerosols
O2 21%, N2 78% Ar 1%
If all water vapour in atmosphere converted to liquid would cover entire earth surface by
1 inch (25mm) smooth layer
Greenhouse Effect and Radiation
2 types of radiation: short wave and long wave
GHG is atmospheric constituent that traps outgoing terrestrial radiation
Water vapour is the most important GHG in atmosphere
Understand the difference between GHG and enhanced GHE
www.notesolution.com

Loved by over 2.2 million students

Over 90% improved by at least one letter grade.

Leah — University of Toronto

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto
Saarim — University of Michigan

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan
Jenna — University of Wisconsin

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin
Anne — University of California

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California
Description
Lecture 4: Atmosphere-Climate System Composition and Structure of the Atmosphere • The very early atmosphere probably consisted of gases, mainly hydrogen and helium, which was abundant in the solar system • Then came the geologic control o Under geologic control, a secondary atmosphere was formed: Out gassing from cooling magma Emissions from volcanoes o Essentially no atmospheric O2, and highly corrosive o Highly energetic-lightning, volcanic activity, high UV radiation • Then the biological control o Anaerobic conditions “Age of Bacteria” o Anaerobic bacteria developed about 3.5 to 4 bya o Could survive in absence of oxygen and began the slow conversion of CO2 to O2 • Gaia Hypothesis o James Lovelock, not about environmental control, life modifies the environment to best suit itself o Atmospheric constituents have been controlled by life to optimize conditions for life o Abrupt change occurred 2.3 bya, Os started to appear o As O2 started to become abundant, some was broken down by the sun’s radiation into atomic O2 and eventually formed ozone O3 o Life started to appear o Evolution of the Atmosphere Once rocks at surface were sufficiently oxidized, more oxygen could remain free in atmosphere There was switch from anaerobic to aerobic condition 2.3 bya 2.3 bya solar output increased and earth was becoming too warm, the switch to aerobic life, reduce the greenhouse gases and cooled the planet Now have lower levels of CO2 in atmosphere than early earth O2 stabilizes at 21%, which is optimal for life on earth • Then came the Anthropogenic control o During Carboniferous Period (290-360mya) life appears on land Sun’s energy converted to plant material (photosynthesis) Decaying plants not fully oxidized Converted to coal and oil under geologic pressure, stored for millions of years We used these fossil fuel for our comfort o Composition now Atmosphere currently consists of water vapour, aerosols (gaseous suspensions of find solid or liquid particles) Water vapour- less than 0.0001% of all the water on earth Aerosols O2 21%, N2 78% Ar 1% If all water vapour in atmosphere converted to liquid would cover entire earth surface by 1 inch (25mm) smooth layer Greenhouse Effect and Radiation • 2 types of radiation: short wave and long wave • GHG is atmospheric constituent that traps outgoing terrestrial radiation • Water vapour is the most important GHG in atmosphere • Understand the difference between GHG and enhanced GHE www.notesolution.com • Some of Sun’s radiation absorbed by natural GHG o If there is no GHG, earth will be very cold (-33), GHG absorb radiation and keeps earth warm o Enhanced GHG, is causes by burning fossil fuel, CO2 emitted, CH4, O2, N2O, CFCs o Helping the inducing of water vapour by increasing GHG into the atmosphere- positive feedback loop • Water vapour is most important GHG in atmosphere • Understand the difference b/w greenhouse effect and enhanced greenhouse effect Atmospheric Moisture • Standard atmosphere o To understand the changes within the atmosphere, have to have a standard o Pressure: 1013.25mb, temperature: 15 degree Celsius, air density: 1225 g m-3 o Air density changes with altitude, it changes rapidly o 4 layers in atmosphere Troposphere- 0-10 temperature decrease with altitude, at surface, heated by sun’s ray Stratosphere- 20-50, temperature increase with altitude, have ozone that absorb UV radiation and turns into kinetic energy of motion Mesosphere- very unstable zone where there is high mixing Thermosphere- lots of O2 and O3, absorbs sun’s rays and turns into kinetic energy of motion o Variations with latitude Troposphere thicker in the tropics, thickness decreases as it goes towards the poles o Latent heat is released when one state changes to another state o Most water vapour enters atmosphere over the oceans o Relative humidity: indicates the amount of water vapour that can still enter the air mass before being saturated o Warm air holds more water vapour o Clouds form as warm air rises, expands, cools- holds less moisture o Lapse rate: change in temperature with heights that is associated with pressure, as pressure decreases, volume increases and temperature drops Warm air rises and it expands- volume increases Air parcel at 0m has a temperature of -10 degrees, it rises at dry adiabatic lapse rate. What is temperature of air parcel at 1km is -20 degrees, if air parcel drops 1 km, it is 0 degree o The adiabatic lapse rate: measure of how much air decreases in
More Less
Unlock Document


Only page 1 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit