CHEMISTRY OF THE ENVIRONMENT (GREENHOUSE EFFECT) Part 1

NOVEMBER 25, 2009
(PHNO) by Dr. Angel Cagandahan de Dios ("The Earth system follows laws which scientists strive to understand," said Dr. F. Sherwood Rowland, a Nobel laureate in chemistry.)

("The public deserves rational decision-making based on the best scientific advice about what is likely to happen, not what political entities might wish to happen." From: Scientists Protest Bush's Misuse of Science | Science Blog)

The above quotes are the author's choice inspirations in the presentation of the lecture to his student. PHNO feels strongly on the proper education of our youth today, especially in subjects that are demanding the world's attention for solutions to make our world a better and safe place to live. PHNO would like to introduce the author, Professor Angel de Dios, Director of Undergraduate Studies and Associate Professor at Georgetown University in Washington, DC. His First Lecture follows the foreword.

PHNO DISCLAIMER: The lectures on 'Chemistry of the Environment' by Professor Dios were uploaded to his website at http://bouman.chem.georgetown.edu and copied/pasted here without permission on November 25, 2009. Here is a foreword by PHNO webmaster authorized by PHNO Editor Sol Jose Vanzi.

FOREWORD: Dr. Angel C. de Dios

A VERY TIMELY  TOPIC FOR A HUGE CHALLENGE TODAY: This is the first part of 2 special lectures Dr. de Dios  presented to his Chemistry students at Georgetown University on Greenhouse Effect: Chemistry of the Environment. I am privileged to have known the author for many years and have met him once when he visited us in Toronto. PHNO is blessed to have always been an estuary of Dr. de Dios's vast knowledge and experience in Science & Technology. This young man who turned 44 last January, has a quick mind for learning and teaching anything thrown his way. Apart from his own field of science, whether it be in music, in research, or even in computers, he often became my fastest resource whenever in need of quick compound and scientific solutions. He is a poet too, especially in the vernacular language. I really think he was a natural born erudite with a passion for learning. I believe the word 'over-achiever' is key since the formation of his being. As a young boy from poor parents, stories were told of Angel walking to school without shoes on his feet. His bio on his website clearly shows that he took his entire education from elementary to university relentlessly on his own facing all challenges and finally winning them through college scholarships, post-doctoral fellowships and other prizes for outstanding accomplishments. He has now seemed to have reached his comfort zone in "over-achievement". He is happily settled and has started a growing family in suburban
Virginia with his wife Mary (with him in photo at right) who, herself has a degree in Pharmacology and their 2 growing children: Alexander, age 3 and 4-month-old baby girl, Amelia Milan. It was in 1992 when Angel completed with top honors his Ph.D. in Physical Chemistry at the University of Illinois in Chicago. He is currently Associate Professor in Chemistry and the Director of Undergraduate Studies at the prestigious Georgetown University in Washington, DC.

I met Angel at my hometown's Internet community website at www.paete.org. It was not long and he showed his passion and dedication to help our school children in our town of Paete, Laguna. Angel was born and grew up in Metro Manila (Malabon) but spent a lot of his summer vacations in Paete, the hometown of his late mother. Soon he was leading the global Paetenians in projects assisting our town in education. Foremost is the Alay Computer project where with his dedication and generous financial and personal help, the computerization of the Paete elementary schools, the municipal building and the first national high school was speedily accomplished. Hundreds of Paetenians abroad who have Internet connections are able to "come home" via the  www.paete.org to virtually live together in constant communication with our town Mayor and his council as well as the students, parents, and the teachers. When the creator and owner of our town website requested Angel to help moderate the online discussion forum (called Usap Paete) he accepted without question and soon enough he was ably administrating it like a professional.

Like all of us Paetenians abroad, Angel shares an undying dream to improve the standard of education for Batang Paete (Youth of Paete) help prepare these school kids for their future's new world of advanced technology. Our parents have gifted us adults the gift of natural skills in woodcarving, farming and fishing, we foresee our kids and their kids to embrace the kind of global community that is going to be their world. Dr. de Dios also leads his Georgetown research group in an ongoing research for a cure for malaria at <http://bouman.chem.georgetown.edu/research.html>. He has a growing repository of Science Lessons used and visited by schools all over the world at <http://www.paete.org/forums/viewforum.php?f=12> & at <http://bouman.chem.georgetown.edu/batangpaete.html

Finally, I still think  Angel has the most unique name of all: Translated in English, his full name means "Angel Cagandahan (Beautiful) de Dios (of God) -  Angel beautiful of God.

Related websites:
Angel de Dios homepage: http://bouman.chem.georgetown.edu 
Georgetown University: http://chemistry.georgetown.edu/people/deDios.html
His biosketch site:
http://www.bahaykuboresearch.net/index.php?module=article&view=42
BATANG PAETE (School children of Paete, Laguna, Philippines)
http://www.paete.org/forums/viewforum.php?f=1
His charity project for the town of Paete:
ALAY COMPUTER

Now here is first part of his lecture:
("CRY OF EARTH: The cry of distress, of pain at the state of the planet has been heeded. No longer can we take the resources of nature as ours to master. No longer can we behave as the conquerors of nature. The path to sustainable development is to respond to the legitimate aspiration of peoples for better living standards while ensuring that future generations retain the qualities of life in harmony with our habitat" Boutros Boutros-Ghali)


CHEMISTRY OF THE ENVIRONMENT
(GREENHOUSE EFFECT)
PART 1

This is first lecture Dr. De Dios presented to his chemistry students at Georgetown University, Washington, DC
Part 2 follows in next PHNO Science & Technology page update.

The following two lectures are based on course materials developed and compiled by Arthur Glasfeld and Margret Geselbracht
of the Department of Chemistry at Reed College. Materials have been specifically drawn (with permission from the authors)
from the following document: Introduction to the Greenhouse Effect

The Sun and the Planets - The Sun is the source of radiation for the planets. One can compare the amount of energy the earth gets from the sun with other sources here.

Some physical constants relevant to the radiation budgets of the planets:

Planet          Distance to sun (km) Solar constant (W m-2) Albedo Radiative temp. (C) Surface temp. (C)
Venus 1.08 x 108  2613 75% -39 427
Earth    1.50 x 108 1367 30% -18 15
Mars  2.28 x 108 589  15% -56 -53 

Table copied from http://academic.reed.edu/chemistry/courses/chem101/Handouts/IntrotoGreenhouseEffect.pdf
The Solar Constant is the amount of energy that falls on a planet, on a plane perpendicular to the rays of the sun. This
constant is a function of the distance of the planet from the sun.

Since a planet cannot have all of its surface perpendicular to the sun, the average Solar Constant for any planet is actually
smaller. For Earth, it is 340 W m-2 (Watt is a unit of power = Joules /second, and the Solar Constant is expressed in terms of
power per unit surface area).

Albedo is the percentage of the sunlight that is reflected from the planet - this is dependent on several factors such as cloud
cover, color of the planet surface, atmospheric dust, etc. Venus has a very high albedo because of its cloud coverage, which
blocks sunlight from reaching the planet's surface.

The Radiative temperature is derived by taking into account the Solar Constant and the Albedo - which gives the amount of
solar energy that is absorbed by the planet's surface. This makes the assumption that when materials absorb light, they re-emit
some of this energy as heat. Because Venus' cloud coverage reduces the amount of sun's radiation reaching its surface, its
predicted surface temperature is colder than that of Earth eventhough Venus lies closer to the sun.

The last column, Surface temperature, demonstrates vividly the Greenhouse Effect. The difference between the
Radiative temperature
and the actual Surface temperature is the consequence of the Greenhouse Effect.

Venus is HOT! Earth is livable! Mars is COLD!

Black-Body Radiation (Max Planck)

Any object at a temperature other than absolute zero emits light. The intensity distribution across the wavelengths
is given by Planck's equation above. Hot objects will emit light at shorter wavelengths compared to cooler objects.

Examples:

The spectrum of stars - using Planck's radiation formula

The Solar Spectrum

http://en.wikipedia.org/wiki/Image:Solar_Spectrum.png

 

 

 

 

 

 


 


Figure copied from : http://academic.reed.edu/chemistry/courses/chem101/Handouts/IntrotoGreenhouseEffect.pdf

Original source: "The Chemistry of the Atmospheres", Richard P. Wayne, 1991

Earth's radiation peaks at about 20 micrometers and covers a range of 5 to 100 micrometers. Therefore, most of
the radiation absorbed by planet earth will be emitted at these longer wavelengths.

Radiation budget


Figure downloaded from NASA; http://asd-www.larc.nasa.gov/SCOOL/energy_budget.html

Original source: Kiehl and Trenberth, 1997

Here's a list that will explain exactly what is going on here, by breaking down the categories
(the following percent signs are relative to the original radiation):

100% Incoming solar radiation


6% reflected by atmosphere
20% reflected by clouds
4% reflected by earth's surface
70% absorbed by planet (atmosphere and lithosphere combined)


70% Absorbed by planet (expanding the last category)


16% absorbed by atmosphere
3% absorbed by clouds
51% absorbed by land and oceans


51% Absorbed by surface


23% lost through evaporation
7% lost through direct heating of air
21% of initial radiation to be re-emitted as blackbody radiation (mostly in infrared)

More on earth's energy balance


The Planets' Atmosphere

Atmospheric composition of planetary atmospheres.

Planet

Atmospheric Pressure


Chemical Composition of Atmosphere (%)
 

N2 O2 H2O CO2
Venus 92 atm <2 <0.001 0.0001-0.3 >98
Earth 1 atm 78 21 0.0001-4 0.035
Mars 0.006 atm 2.5 <0.25 <0.001 >96

Table copied from http://academic.reed.edu/chemistry/courses/chem101/Handouts/IntrotoGreenhouseEffect.pdf

The pressure of the atmosphere is related to the surface temperature of the planet.

Venus is HOT! Earth is livable! Mars is COLD!

Venus is 92 atm, Earth is 1 atm, Mars is 0.006 atm

Greenhouse Effect

http://earthguide.ucsd.edu/earthguide/diagrams/greenhouse/

The "greenhouse effect" is the warming of climate that results when the atmosphere traps heat radiating from
Earth toward space. Certain gases in the atmosphere resemble glass in a greenhouse, allowing sunlight to pass
into the "greenhouse," but blocking Earth's heat from escaping into space. The gases that contribute to the
greenhouse effect include water vapor, carbon dioxide (CO2), methane, nitrous oxides, and chlorofluorocarbons (CFCs).

Life on Earth depends on energy coming from the Sun. About half the light reaching Earth's atmosphere passes through
the air and clouds to the surface, where it is absorbed and then radiated upward in the form of infrared heat. About
90 percent of this heat is then absorbed by the greenhouse gases and radiated back toward the surface, which is
warmed to a life-supporting average of 59 degrees Fahrenheit (F) (15 degrees Celsius (C).

-NASA Fact Sheet NF-182 June 1993

 


http://en.wikipedia.org/wiki/Image:Atmospheric_Transmission.png

Greenhouse molecules http://www.wwnorton.com/college/chemistry/chemconnections/Warming/pages/molecule.html


Infrared Absorption

 

 

The above copied from http://academic.reed.edu/chemistry/courses/chem101/Handouts/IntrotoGreenhouseEffect.pdf


Contact Info: Dr. Angel C. de Dios
Department of Chemistry
Georgetown University
Washington, DC 20057
Office: 602 C Reiss Science Building
Phone: (202) 687-0670
Email: dediosa@georgetown.edu


Chief News Editor: Sol Jose Vanzi

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