Evaluation # 8

Hello Professor,

This blog will focus on the second part of the Climate lab. The reason being, is that in the lab, the concept was still a little fuzzy and by studying and depicting it here, I am hoping to fully understand the two dimensional climate model explained in Richars Wolfson's "Energy, Environment, and climate". 

The purpose of the two dimensional climate model is to illustrate in a simplified way how the earth's energy balance works and how the energy exchange between the surface and the atmosphere functions. As we know from previous chapters, the energy balance of the earth entails that the same amount of energy enters from the sun as it is reflected back to space. 

Due to the emissivity(the effectiveness of molecules in absorbing and radiating energy) of the molecules in the atmosphere, the manner in which the energy leaves the earth is not as uniform as when it enters. Almost 100% of the earth's energy is derived from the sun. Even though, the earth receives 235 W/m^2 of solar energy, not all of it reaches the surface. A large amount of the solar energy is directly reflected back to space by the greenhouse gases. This is attributed to their high emissivity rate, which is not constant and depends on the atmosphere's temperature and molecular concentration of greenhouse gases. 

The remainder of the solar energy that is not directly radiated back to space, reaches the earth's surface. Although the radiation of the surface depends on the surface's temperature, in total its emissivity is close to one. This means that the earth's surface absorbs and emits energy very well.  As a result, the energy that reaches the earth is reflected back to space. This is how the earth's energy balance occurs.

However, before earth's surface energy is reflected back to space, it is absorbed by the atmospheric gases of the lower atmosphere due to the difference in temperature between the earth's surface and the atmosphere. This difference in temperature, absorption of energy, and retention of energy is what we refer too as the greenhouse effect. One can go as far as to deduce that life is possible on earth due to the presence of greenhouse gases. Otherwise the earth's average temperature would be 254 Kelvin or -19. 15 Celsius, which would be way beyond water's freezing point. 

Blog Abstract

        Blog Abstract

Blog #1: September 10

“Green, Sustainability, and Systems Approach”

This blog defines, explains, and analyses each concept.

 

Blog #2: September 14

“Opinion of the Week”

This blog expresses its opinions about the presentation held that week. It also advises for a class blog in which every student can have access to the power point of the presentations held so a more profound understanding can be achieved.

 

Blog #3: September 21

“Opinion of the Week”

This blog admires the teaching methodology, which encompasses a balance of lecture with individual teaching trough research.

 

Blog #4: September 21

“Evaluation on the First Plenary and Lab”

This blog expresses a positive opinion of the first plenary session, which was about sustainability. The second part of the blog expresses contentment with the lab on solar constant because it propelled the internalization and understanding of that concept.

 

Blog #5: October 5

“Systems Approach and Kafka”

This blog appreciates the summary given in class of the terms “green”, “sustainability”, and “systems approach”.  It also makes the comparison of the concept of systems approach with Franz Kafka’s story of “The Castle”.

 

Blog #6: October 13

“Color”

This blog extends on lab conducted in class on color. It explains how color works and explains why we perceive the colors we do.

 

Blog #7: October 19
“Thermodynamics”

This blog explains and focuses on the three ways of heat transfer: convection, conduction, and radiation.

 

Blog #8: October 26

“Beyond Oil”

This blog focuses on the explanation of Hubbert’s Peak and well as the concepts of “Hubbertians” and “Cornucopians” raised in the book “Beyond Oil” by Deffeyes.

 

Blog #10: MIDTERM

Blog #11: November 9

“Coal War”

This blog is about the article on the Scientif American magazine called “Coal War: Georgia Halts Construction of New Coal- Fired Plant”. It resumes it while giving an analysis of its significance on environmental field. 

Class Assignment from November 14

Emissivity:

As we know, heat can be transferred through convection, conduction, and radiation. As long as objects have a higher temperature than absolute zero (-273 Celsius), its molecules vibrate as a result they are constantly absorbing and emitting electro-magnetic radiation. For example, if an object is hotter than its surroundings, it will emit energy and if is colder, it will absorb energy from its surroundings. As a result, the net flow of electro-magnetic energy between two objects depends on the temperature difference between the two.

 

So what is emissivity?

Emissivity is the property that each object has to either emit or absorb electro-magnetic energy. The emissivity of an object depends two things: Its material and surface area.

 

The scale 0-1 describes the objects efficiency as an emitter and absorber.

è   A black object is a perfect emitter/absorber.

è   A shiny object is a poor emitter/absorber.

 

One must take into account that the objects efficiency rate as an emitter is equal to its efficiency as an absorber!

 

Since emissivity describes the electro-magnetic energy exchange between two objects, the emissivity for visible light (low wavelength) is different for that of infrared (high wavelength).

 

Question 3:

In what sense is radiation the only heat-transfer process affecting the planet’s energy-balance? In what sense do other processes play a role?

 

The earth receives all its energy from the sun through radiation and most of it is reflected back to space. The term energy balance refers to an equal amount entering and leaving a system. On earth, the energy balance is achieved through electro-magnetic radiation. Energy from the sun enters the earth in two forms, through light (short wave energy) and through infrared radiation (long wave energy). The short wave energy enters and leaves the earth without inhibition since none of the atmospheric gases absorb visible light. Yet molecules in the atmosphere such as carbon dioxide, nitrogen, water, and methane absorb the infrared radiation, or long wave energy. The short wave absorption by those gases is the key element in the establishment of the planet’s energy balance because some energy is then prevented from leaving the earth. As a result of the atmospheric gases the earth’s average temperature is raised from 254 Kelvin to 287 Kelvin. Our planet’s energy balance consists of an equal rate of short wave energy that enters and leaves the planet, yet the entrance and exit of long wave energy is not the same.

Other processes like clouds, oceans or geographical variations influence the planet’s energy balance. However, they are rather ignored in the big picture because their influence on the energy balance is minimal in comparison to the atmospheric gases. Yet the increase of fossil fuel consumption, which has significantly increased the presence of atmospheric gases, especially CO2, has contributed in altering the earth’s energy balance. The reason is that now more short wave energy is absorbed. As result, more energy from the sun is retained in the atmosphere than it naturally should!

Evaluation # 7

Good Evening Professor,

This week, my group had to work on the article "Coal War: Georgia Halts Construction of New Coal- Fired Plant". Our article was written on July 3, 2008 and depicted the first time that a court denied the continuation of the construction of a coal-fired plant in Chattahooche River in Georgia. The jurisdictional reason was that the permit for the plant neither contained a cap of CO2-emissions nor was seeking to implement any technologies to control them. The plant aimed to produce 1,200 mega-watts and as a result this plant would have emitted 8-9 million tons of CO2 into the atmosphere. In the United States the coal production is responsible for 40% of the C02- emissions. Additionally, coal fired plants have the highest output rate of Co2 per unit of electricity among all fossil fuels. Yet coal is also responsible for 50% of the U.S energy.  

This denial of the continuations of the construction of the coal-fired plant is quite significant in the political as well as in the environmental field since it is the first time that the Clean Air Act has been enforced by the Energy Protection Agency.  The Clean Air Act has been around since 1963. This legislation seeked to reduce smog and air pollution in the sixties. Realistically, the ratification of this act by congress was more or less a charity act for most people were not concerned with the environment back then. As the years passed, this act was modified and amended. The reduction of acid rain called upon and so was the concern of the ozone depletion. With time, this act became for specialized and dealt with pressing environmental issues, yet no organization or government body was assigned to enforce the act. This caused the act to be politically insignificant. Yet in May 2008 a Supreme Court Ruling gave the Energy Protection Agency the power to enforce the Clean Air Act that had been on the shelves for quite some time. This ruling changed the game since now they possess the political power to control, prohibit, and regulate issues associated with the environment. Finally, environmental protection can begin to happen since it can now be politically enforced!

Of course, the power company responsible for the power plant is appealing the the ruling of the Supreme Court of Georgia, arguing that when the permit was given, the EPA did not yet have the power to enforce the Clean Air Act. This is a valid point. The resolution of this political dispute remains to be seen. Yet we cannot deny that the denial was a stepping stone in environmental politics. 

Bibliography:

Scientific American: "Coal War: Georgia Court Halts Construction of New Coal-Fired Plant"

The Sierra Club Organization: "http://nevada.sierraclub.org/conservation/powerplants/EECcoalplant.html"

Energy Protection Agency, The Clean Air Act: "http://www.epa.gov/air/caa/"