Syllabus handed out and key points reviewed;
course web site (under construction at www.ltrr.arizona.edu/nats101) explored;
Daily readings from Mackenzie textbook are listed in syllabus, but additional
readings will be announced and made available through course web site;
2 questions on first quiz will come from list of questions at end
of syllabus.
Class roll
was obtained by passing around lists where students indicated their presence
Mention of
some of the class content (examples of great concern with cooling temperatures
in the 1970s; the graph of changing atmospheric CO2 concentration
since 1958 that some have called the most important graph of the 20th
Century; the graph of changing CO2 concentration over the last
12000 years)
Global Change IQ quiz given in last 10
minutes to get some idea of prior global change knowledge of students
coming in to class. (no grades will be assigned)
Note:
15 student volunteers are needed
to be group activity group leaders (eligible for 5 points extra credit)-
send e-mail with your interest to sleavitt@ltrr.arizona.edu
Note:
Everyone should send Li Cheng
(lcheng@ltrr.arizona.edu) a message indicating
what e-mail account you would like us to use for the course listserve
forum (deadline 5pm Jan. 29) This is a course requirement.
Intro to grand story of epic proportions (sort of like Star Wars, Bible,
etc) known as The
Periodic Table,
that establishes a context of time and space in which our world exists
Cast of characters
Elements
arranged according to increasing Atomic Number (number of protons).
(This arrangement
is also related to filling of electrons in discrete electron “shells”)
Each
element has name and 1- or 2-letter shorthand notation.
When
an atom is “neutral”, it will have an equal number of protons (+) in nucleus
and
electrons
(-) orbiting nucleus.Neutrons
(no charge) also can reside in nucleus at the center of atoms.
Characteristics of matter
All
matter is made of small particles (atoms and their consituents) Atoms of the
same element have similar chemical properties Atoms are not divided
by chemical reactions Chemical reactions involve
electrons; nuclear reactions involve protons/neutrons (in a column of period
table different elements may behave similarly in chemical rxns)
Isotopes of a given element have same number of protons,
but different numbers of neutrons
Scientific notation (examples)
Conversion of units (examples)
Moles (number of atoms in the atomic weight [in g] of an element= 6.02x1023
atoms for any element)
Student Conservations Association information (www.theSCA.org) internship opportunities
Finish questions on worksheet handed out last time (conversions,
scientific notation)
Back to epic story in Periodic Table of Elements:
Only 2 elements,
H & He, were formed in “Big Bang” 15 billion years ago
when all matter in universe was contained at a point (“singularity”).Only H and He formed because universe was rapidly
expanding (cooling) and there were progressively fewer interactions between
atoms, neither of which was favorable to formation of heavier elements.Thus, the carbon (C) atoms in your hair and Gold (Au)
and silver (Ag) atoms in your teeth did NOT form during the Big
Bang.
Elements from
lithium (Li) to iron (Fe) produced in the interior of normal
stars by “fusion” processes, i.e., lighter elements being combined to
manufacture heavier elements.For
example, in our Sun, fusion takes place converting 4 hydrogen atoms to
one helium atom; the mass of the helium atom is less than the 4 hydrogens,
so the difference in mass is what was converted to energy that contributes
to the internal heat of the Sun (E=mc2).The energy from such nuclear reactions (involving nuclei of atoms)
>> energy from chemical reactions (involving electrons of atoms).
Observations
of the Cosmos that fit Big Bang formation of 2 elements in Periodic Table:
1. High cosmic
abundance of H and He; abundance generally declines with
increasing atomic number but there is also a peak at Fe (iron)
2. Galaxies
moving away from us at high speeds; the more distant the faster they are
moving away (Hubble telescope deep-space images; Doppler effect
and shift to lower frequency and longer wavelengthelectromagnetic
radiation as source moves away from observer; distinct absorption
lines of light wavelengths by sodium atoms lead to observation of "red
shift")
Eye-popping,
jaw-dropping, awesome demonstration of the Big Bang, in full special
effects mode with Dolby® Surround-sound®,
and 3-D glasses
The fusion
taking place in the Sun and other stars represents a tremendous energy
source, and research has been directed at trying to promote controlled
fusion reactions on Earth as a limitless source of energy (The
world already has many fission reactors in which large radioactive
elements such as uranium, decay and release energy)
Elements up
to Iron can be produced by fusion because energy is released; Elements
beyond (heavier than) iron cannot be produced by fusion, but can be produced
by high fluxes of neutrons, such as occur when stars explode (supernova).Our sun has all of the elements of the Periodic
Table, therefore it must have formed from remnants of other stars that
have gone through their full life-time of fusion reactions and explosive
instabilities
Laws of Thermodynamics
First Law-
Energy cannot be created or destroyed, but it can be converted from one
form to another (examples of energy- heat, like, kinetic energy, electrical
energy, potential energy of petroleum, food and gravity)
Second Law-
No energy transformation is 100% efficient or Energy can be converted from
one form to another but in all conversions there is formation of some
‘low quality’, ‘non-usable’ heat or Heat cannot be completely
converted to work or Universe runs down as energy is dispersed to low-quality
heat energy or All systems tend to become
random (or dispersed) on their own.Entropy
is a measure of randomness, or dispersion or disorder
The quiz Wed will be given in the first 20 minutes (maybe 25 minutes) of class, with lecture to follow
in remainder of period.There
is sample quiz on web page. Preparation instructions for Group Activity 1 (on Friday) are also given on web page; the
groups are also listed on web page.
People who have not yet sent Li an e-mail indicating the e-mail address
they would like subscribed to the forum have until 5pm Wed to do so.
Origin
of Solar System There was
about 10 billion years between the Big Bang and the origin of our
Solar (Sun) system Our solar
system is made of all the elements of the Periodic Table but only He is
being
produced in our solar system currently (in the Sun); therefore all of
the
elements had to have been produced in the 10 billion years before the solar
system was formed. (our system is from the remnants of other stars) Solar Nebula
Hypothesis has solar system forming from a rotating ball of dust and
gases
that flattened to a disk shape.Most
of the mass was in the center
and
the pressure and temperature in that environment ignited hydrogen
“burning”
(fusion). Matter was
distributed in the solar system such that the internal 4 planet are more
dense
and rocky “terrestrial” planets and the outer “Jovian” planets are
lower
density, “icy” planets composed of lighter elements/frozen gases.
Over
100 other planets have been observed around other distant stars, but
most
are quite different than ours (hotter and much, much larger!) Newton’s
Laws 1st-
Every object persists in a state of rest or in uniform motion in a straight
line
unless
acted on by an external force to change that state. 2nd-
The change in velocity (= acceleration) with which an object moves is
directly
proportional to force applied and inversely proportional to the mass
of the object (a=F/m)
3rd- Every force or action
has an equal and opposite reaction (conservation of momentum) Law of Universal
Gravitation- any and all objects exert an force of attraction between
them proportional to the product of their masses and inversely to the
distance between them squared. (F= G x (m1 x m2)/r2)
Quiz 1 from about 12:02 to 12:20 after class took randomly
assigned seats.
Deadline for students to send message to Li about listserve is today at
5pm. Reminder
of Instructions for Preparation for first group activity on Friday
appeared on screen from class web page- Each student must bring at least
2 photocopies/printed
pages of material (from web/library) to class Friday about the element
their group is exploring (particularly information relevant to the questions
listed on the web page).
Law of Universal Gravitation- example of gravitational
force exerted by nearest star (other than Sun) on you at birth vs. the
gravitational force exerted by the doctor who delivered you.
Structure of the Earth
During early
stages of Earth history, our planet was at least partly molten resulting
from heat of collisions and gravitational potential energy converted to
heat energy (decay
of radioactive elements was also important source of heat over all of
Earth’s history)
During this
early period, Earth began to “differentiate” into layers with heavier
material “sinking” to interior and lighter material “rising” to surface. Consequently
Earth’s core is made predominantly
of iron and nickel (like some meteorites).The mantle
layer above the core is primarily magnesium
(Mg) and iron (Fe)
silicate (Si and O) rock, and the crust
on the surface is composed of silicate rock with less Fe and Mg and more
K, Na and Al.
Even though no
one has ever drilled or dug to the mantle, we have samples of the mantle
courtesy of plate tectonics.The
sample passed out in class was
from the upper
mantle, brought to the surface in Norway a billion years ago; the rock
is called eclogite.
Presentation
about the Student Conservation Association intern program by Dan Pascucci,
which finished with a rousing song designed to help us remember www.theSCA.org
Class broke out into the 15 groups and completed Group Activity 1 Revisit group activity #1 with slides of mining activities around
U.S. and some of the environmental problems associated with mining
Quiz 1 handed back and answers given and discussed (+1
grade adjustment added to raw score)
Make-up opportunities for GA #1- Students asked to provide
availability for BOTH 1-2 Wed and 9-10 Friday for POSSIBLE make-up. Send
your availability by e-mail to sleavitt@ltrr.arizona.edu
Structure of the Earth
Differences
in chemistry among layers (for example low SiO2 in mantle and higher in
continental crust, and more Fe in mantle and less in crust) is consistent
with
Earth’s “differentiation” into the layers early in its history.Contintental crust is
referred to as having a granitic composition; oceanic crust a basaltic
composition. The ocean crust is also called “mafic” (dominated by Mg and Fe),
whereas the
mantle is ultramafic in composition.
Crust and
rigid upper mantle constitute the “lithosphere”.The lithosphere rides over the portion of the upper mantle (asthenosphere)
that flows (heat from Earth’s interior
leads to convection processes in the asthenosphere).The plates move (cm per year)
and interact with each other in a dynamic system known as “plate tectonics”.
There
are 3 different types of plate boundaries.
Plate tectonics and types of plate boundaries (plates colliding = “convergent”
boundary;
platesmoving
apart = “divergent” boundary; plates sliding past each other = “transform”
boundary. In
many cases, besides earthquakes and volcanoes, the location of ore deposits
of specific metals
is related
to plate tectonic and plate boundaries.The richness of metal resources of a country
are
dictated by their
current and past position with respect to plate tectonics and other ore-forming
processes.
Reminder
of GA1 make-ups today 1-2pm and Friday 9-10am (room 104 W. Stadium) Revisit
group activity #1 with slides of mining activities around U.S. and some
of theenvironmental problems associated with mining
Major
natural global change events in the first 4.50 billion years of Earth
history- Earth origin; early heating of Earth and "differentiation"
into layers; origin and abundance of life; cyanobacteria and changing atmospheric
oxygen concentrations; banded iron formations (BIF) representing precipitation
in early oceans of Fe2+ with
oxygen liberated by photosynthesis,
thus preventing an early build up of oxygen; "ice house"
and "hot house"
periods"; early Sun “paradox” when solar luminosity was 30% less
than
present and why the oceans
did not freeze (answer= "greenhouse gases" such as CO2
may
have been at very high
concentrations in early Earth atmosphere) Today’s
atmosphere dominated by nitrogen (78%), oxygen (21%), argon (1%) and “trace
gases” Origin of atmosphere- "outgassing" ofEarth's interior=> H2O condenses
to form oceans, CO2 and SO2
dissolve in water; H2 escapes to space, N2 and Ar
build up, photosynthesis builds up O2 (after BIF oxygen “sink” was filled) Demonstration
of 4 atmospheric gases, some in unusual (cold) forms
Demonstration
of the relationship of temperature, pressure and volume for gases, known
as the
“universal gas law” => the product
of volume ´ temperature is proportional
to temperature,
ie, if temperature is decreased,
you will reduce pressure and/or volume, and conversely if
temperature is increased, you
will increase pressure and/or volume. In-class writing exercise to describe experiment and explain the
cause(s) of the observations.
Today’s atmosphere dominated by nitrogen (78%), oxygen (21%), argon (1%)
and “trace gases”.
If volcanic gases being emitted
today are an indication of the gases of volcanoes 4 billion years ago,
they give us a hint about the
evolution of the atmosphere after initial
"outgassing"
ofEarth's interior=> H2O
condenses to form oceans, CO2 and SO2 dissolve
in water eventually forming
limestone and Ca-sulfate deposite; H2 escapes to space, N2
and Ar build up;
photosynthesis builds up O2
(after BIF oxygen “sink” was filled), although “photodisassociation”
of water vapor molecules in
upper atmosphere also produces H2 and O2. Major gases (N2, O2, Ar) tend to have constant
concentration no matter where and when they are measured
(for example, N2
concentrations are very constant everywhere in the world throughout the
year),
but trace gases tend
to be more variable depending on where and when measured (for example,
H2O
concentrations at a location
may vary seasonally (ie, summer and winter) and there can be difference
in concentration depending
on where you are in the world, eg, rainforest versus desert)
Sources (mechanism for gas getting into atmosphere), sinks (mechanism
for removing gas from atmosphere) and
importance of some major and
trace gases; for example, (a) photosynthesis is a mechanism (source)
that produces oxygen (CO2
+ H2O=> CH2O
+ O2 in the presence of chlorophyll and with energy from sunlight),
(b) we need oxygen to live (importance),
and (c) combustion processes can remove oxygen from
the atmosphere (sink).An additional source of this information can be found in “Trace
Gases” module at http://www.hwr.arizona.edu/Alpine/IGCL/home.html,
and in table shown in class.
A handout
involving energy and electromagnetic radiation. Examination of a few of the
trace gases (in table from Feb. 7 classnotes), for example water vapor,
carbon dioxide, nitrogen oxide, sulfur dioxide and ozone that are central
to many of
the global change problems on which we will focus in class. We live in the bottom of a
"sea" of air, with greatest atmospheric pressure at the Earth's
surface (at sea level) Relationship of Fahrenheit,
Celsius and Kelvin temperature scales Temperature structure of atmosphere--
averaged over the whole planet and over the whole year,
we see temperature change as we go upward into the atmosphere as follows: Average surface temperature
is +15C (Earth’s surface would be -18C if no greenhouse gases were present). As you go further upward, temperature
decreases to about -57C at a height of 10 km, which is the top of
the lowest atmospheric layer (known as the “troposphere” in which we live,
contains nearly all weather
on Earth, and has abundant vertical and horizontal air motion) The thin layer above the troposphere
is called the tropopause where temperature remains constant as you
continue to go upward As you continue further upward,
temperature then starts to warm in the next layer (“stratosphere”, contains
the ozone later where absorption of solar ultraviolet radiation contributes
to the increasing temperature,
and air motion is dominantly horizontal) until it is a balmy 0C at the
top of the stratosphere at 50 km. Above the stratosphere, temperature
is constant in a thin layer known as the “stratopause” and then
begins to decrease in the “mesosphere” What is the causes of Earth
seasons? Electromagnetic radiation is
means by which energy is gained and lost by the Earth. Electromagnetic spectrum in
handout with each category of radiation defined by wavelength (l). “Rules of Electromagnetic (EM)
Radiation”- (1) The hotter the object, the shorter the wavelength
of peak radiation (Wien’s Law determines the peak wavelength, and the
temperature of
any object will determine the wavelength), (2) Shorter wavelengths have
greater energy,
(3) Energy emitted as EM radiation increases as the 4th power
of an objects temperature
(An object twice the temperature of another emits 16 times as much energy),
(4) Objects
emit visible light (reddish glow) as objects reach a temperature of about
550-600C.
Reminder to bring in 2-3 pages about your country’s water
resources to Friday’s GA2.
Graded writing exercise was handed back; Quiz 2 next Wednesday- a sample
quiz 2 will appear on website on
or before
Monday morning
Reminder of EC opportunities at Tucson Gem and Mineral Show this weekend,
and Gold exhibit at Flandrau Planetarium
Cause of seasons= tilt of the Earth’s axis: when our hemisphere is tilted
toward the Sun we have summer,
and
when it is tilted away from the sun we have winter (seasons are opposite
for S. Hemisphere,
but
is summer occurs when it is tilted toward sun).
More “Rules of Electromagnetic (EM) Radiation”- Wien’s Law- we calculated
peak wavelengths of terrestrial [in the infrared]
and solar
[in the visible] radiation), and an object twice the temperature of another
emits 16 times as much energy.
Atmosphere absorbs some wavelengths of terrestrial and solar radiation
(Fig. 3.2).Incoming solar radiation has much
of its UV
radiation removed by oxygen and ozone; outgoing terrestrial radiation
is absorbed by greenhouse (GH) gases
such as water
vapor and CO2.
Our detailed definition of the greenhouse effect- the atmosphere is “transparent”
to (ie, it does not absorb) much of the incoming
solar radiation
(like the greenhouse windows), but greenhouse gases effectively absorb
many wavelengths of the outgoing
terrestrial
radiation and prevent the energy from escaping to space (like greenhouse
windows keeping heat energy in
the greenhouse).Suggested that the greenhouse effect is a good
thing, without which the Earth’s average temperature
would be
33C colder; it is the “enhanced greenhouse effect” that is the major global
change problem we are currently facing.
Fig. 3 was introduced in terms of the fate of incoming solar radiation
(most of which [70%] is absorbed by Earth and atmosphere,
and
30% of which is reflected by the atmosphere and Earth immediately back
to space.The fate of the 70% absorbed
will
be discussed next lecture.