Fri. Feb 3
For people who
missed Thursday’s group activity 1 make-up at
Required reading
on Earth reaching a “tipping point” (a
point of no return to a planet with which we are not familiar)-
Washington Post
Reminder that water vapor (H2O) and carbon dioxide (CO2) from our list of trace gases are the 2 most important greenhouse gases on our planet.
We live in the bottom of a "sea" of air, with greatest atmospheric pressure at the Earth's surface (at sea level)
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 +15°C (Earth’s surface would be -18°C if no greenhouse gases were present)
As you go further upward, temperature decreases to about -57°C at a height of 10 km, which is the top of the lowest atmospheric layer (known as the “troposphere”, in which we live)
“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 0°C at the top of the stratosphere at 50 km
Homework: fill in table below:
|
Scale |
Absolute zero |
Freezing Temp of Water |
Boiling Temp of Water |
Earth's Temperature |
|
ºF |
|
32 |
|
|
|
ºC |
-273 |
|
100 |
15 |
|
K |
|
|
|
|
Did combustible test to verify the liquid in test tube cooled with liquid N2 was in fact liquid O2
What is the cause of Earth seasons? (tilt of Earth’s axis)
Electromagnetic radiation is means by which energy is gained and lost by the Earth.
Electromagnetic spectrum subdivided into categories of radiation defined by wavelength (l, page 74 of textbook).
“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- we did calculation to demonstrate 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.
Wed. Feb 1
Two make-up
opportunities for GA #1- Today
Extra Credit opportunity announced that is related to Tucson Gem, Mineral, Fossil Shows
2005 was warmest year on record (see additional interactive info on greenhouse gases)
Discussed description of demonstration on Monday related to PV=nRT
Today’s atmosphere dominated by nitrogen (78%), oxygen (21%), argon (1%) and “trace gases”, i.e., it is an “oxidizing” atmosphere. 4.6 billion years volcanic gases were being emitted containing H2O (dominant), CO2, SO2, H2S, HCl, H2, CH4, and N2 during initial "outgassing" of Earth's interior, i.e., a “reducing” atmosphere. H2O condenses to form oceans; H2 escapes to space; SO2 and CO2 readily dissolve in ocean and precipitate as gypsum and limestone, respectively; photosynthesis builds up O2 (after BIF oxygen Fe2+ “sink” that removes oxygen became saturated), although “photodissociation” of water vapor molecules in upper atmosphere also produces small quantities of H2 and O2. Photosynthesis is a process/mechanism (“source”) that produces oxygen (CO2 + H2O => CH2O + O2 in the presence of chlorophyll and with energy from sunlight).
We can think about mechanism(s) that represent the reverse reaction: CO2+H2O => CH2O + O2, namely respiration, combustion, decomposition. Whereas photosynthesis is a “sink” for CO2 (it removes it from atmosphere) and “source” of O2, the reverse equation represents a source of CO2 and a sink for O2
Sources (mechanism/process for gas getting into atmosphere), sinks (mechanism for removing gas from atmosphere) and importance of some major and trace gases; for example, H2O and CO2 are most important greenhouse gases on Earth. Respiration (the reverse reaction of photosynthesis) is a mechanism (sink) to remove oxygen from the atmosphere (CH2O + O2 => CO2 + H2O) The same equation can likewise represent combustion processes that also remove oxygen from the atmosphere (sink).
Mon. Jan 30
Quiz 1 handed back. Average raw score (out of 25) was 20.4. We went over answers of most missed questions. I will add 1 “exam adjustment” point to your raw score in my final recorded grade for you.
Make-up
opportunities for GA #1- Wed 1-2 (TITANIUM); Thursday
Students interested in field trip were invited to send e-mail requesting a seat on the field trip to sleavitt@ltrr.arizona.edu
Announcement of discovery of distant Earth-like planet was made last week (only about 5 times larger than Earth but orbiting around red dwarf). Try the “Other Worlds” interactive link on the site to learn the different mechanisms whereby astronomers discover these planets.
Review Earth timeline of major natural global changes, including origin and abundance of life; cyanobacteria (stromatolites) 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 in the atmosphere until all of the Fe2+ was “used up”.
Slides of mining activities around
Implicit lesson of GA1- elements have different important uses in today’s society, but there is
unequal distribution of concentrated elements (ores) and their production around the world.
Demonstration of 4 atmospheric gases (N2, H2O, CO2 and O2), 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 the experiment the class observed and then explain the cause(s) of the observations.
Fri. Jan 27
Group Activity 1- important elements/metals in today’s
society.
Wed. Jan. 25
Quiz 1 from about
Deadline for
students to send message to Rebecca about listserve
was
Reminder of Instructions for Preparation for first group activity on Friday- 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 (information relevant to the questions listed on the web page). Typewritten personal notes could be substituted if the sources are all cited.
Plate tectonics and types of plate boundaries (cont’d)
There is heterogeneous distribution
of chemicals across the Earth’s surface. In many cases, besides earthquakes and
volcanoes, the location of ore deposits of specific metals/elements is related
to plate tectonic and plate boundaries.
The richness of metal resources of a country is dictated by their
current and past position with respect to plate tectonics ore-forming processes,
and other ore-forming processes such as related to climate.
Important global changes over the first 4 billion years of Earth history, including the Earth response to 30% lower luminosity of early sun, and changes in CO2, temperature and oxygen in our atmosphere (Fig. 7.5 in textbook); Cyanobacteria (stromatolites) 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 in the atmosphere. These were profound “natural” global changes with no influence of humans
Mon. Jan. 23
The quiz Wed will
be given in the first 20-25 minutes
of class, with lecture to follow as is customary. There is sample quiz on web page with
answers. Also, the answers to the syllabus questions are now written on the web
syllabus. If you are DRC student,
request a seat in room 312, and you can have more time.
Preparation instructions for Group Activity 1 (on Friday) are also given on web page; the groups are now listed on web page.
People who have
not yet sent Rebecca an e-mail indicating the e-mail address they would like
subscribed to the forum have until
5pm Wednesday (1/25) to do so without losing credit (Everyone must
send Rebecca e-mail).
Thermodynamics further explored with example of water behind a dam and the energy it contains, how it is transformed, and its ultimate source,
Structure of the Earth (heterogeneous distribution of chemicals with depth=layers)
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.
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.
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. Continental 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”.
Plate tectonics
and types of plate boundaries (plates colliding = “convergent” boundary; plates
moving apart = “divergent” boundary; plates sliding past each other =
“transform” boundary). Caused by convection (flow) in upper mantle. Contributes to lateral heterogeneous distribution of chemicals
across the Earth’s surface. Boundaries associated with earthquakes and
volcanoes.
Fri. Jan. 20
Some students are in desperate need of a notetaker, please let me know ASAP.
“In Praise of Petroleum?”, an article for class to contemplate a possible “better use” of oil.
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
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. There are also satellite planets (moons) orbiting around many of these planets, such as Titan. Over 120 other planets have been observed around other distant stars, but most are quite different than ours (hotter and much, much larger!)
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 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)
Wed. Jan. 18
We have several people in class who need a notetaker; all you will need to do is take good notes and arrangements will be made to get copies to the students.
Wavelengths (short wavelengths correspond to low pitch for sound waves, and red color for visible light waves; long wavelengths correspond to high pitch for sound waves, and purple color for visible light waves)
Back to epic story in Periodic Table of Elements:
Only H and He formed in Big Bang (13-15 billion years ago) because universe was rapidly expanding (cooling) and there were progressively fewer interactions between atoms, neither of which was favorable to formation of heavier elements. Evidence of the “Big Bang” event is seen in 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 wavelength electromagnetic radiation as source moves away from observer; distinct absorption lines of light wavelengths by sodium atoms lead to observation of "red shift"). Video replay of Friday’s eye-popping, jaw-dropping, awesome demonstration of the Big Bang, in full special effects mode with Dolby® Surround-sound®, and 3-D glasses
Elements from lithium (Li) to iron (Fe) (also He) 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 (1 proton in each nucleus = 4 nuclear particles) to one helium atom (2 protons and 2 neutrons in nucleus= 4 nuclear particles); 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); 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 that are captured in the nuclei of existing atoms; such neutron fluxes occur in interior of massive stars and when stars explode (supernova). Our sun has all of the elements of the Periodic Table, but it is only making He through fusion- Why?
Reviewed last Friday’s homework exercise on scientific notation, Periodic Table of Elements, and conversions; students are referred to web site under “Homework” link to homework 1 (2001) with more practice and descriptions of how to do these things.
One question on Cerceo reading will also appear on quiz 1.
Fri. Jan. 13
Hand-out (atom size [diameter, mass], moles, speed of light, conversions, etc, Periodic Table)
We need about 2 more students as group leaders (who will earn up to 5EC points, other than 31H students).
Also, we need at least one student who takes notes well to arrange to share them with DRC students.
The 535AD global catastrophe was mentioned; Cerceo article linked on syllabus and “readings”
Characteristics of matter
All matter is made of small particles (atoms and their constituents)
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)
Periodic Table
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.
Scientific notation; Conversion of units; Moles (number of atoms in the atomic weight [in g] of an element= 6.02x1023 atoms for any element)
Intro to grand story of epic proportions (sort of like Lord of the Rings, Star Wars, Bible, etc) known as The Periodic Table, that establishes a context of time and space in which our world exists:
Only 2 elements, H & He (the most abundant in the Universe), were formed in “Big Bang”; Evidence of the “Big Bang” event is seen in Galaxies moving away from us at high speeds; the more distant, the faster they are moving away (Hubble telescope deep-space images.
Homework 2 was
given on back of Periodic table; it will not be graded. If everything is
unclear, an old homework on the “homework” link has lots of explanation about
scientific notation, graphs, conversions, etc (it is not to be turned in)
Wed. Jan. 11
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; at least 2 questions on first quiz will come from list of questions at end of syllabus.
Lab. of Tree-Ring
Research, Prof. Leavitt’s home department has been involved with research
of the ancient
bristlecone pine trees in
Course content involves Earth’s systems, natural and human-induced mechanisms of global change, and nature of global changes. For reference, a description of “global cooling” and cries for action (1970s) was given, as was the fate of polar bears.
Student can earn up to 7 Extra Credit points that will be added directly on to their final cumulative course score (a number between 0 and 100%) –WOW!
Note: Everyone should send Rebecca Franklin (rebecca@ltrr.arizona.edu) a message indicating what e-mail account you would like us to use for the course listserve forum (deadline 5pm Jan. 25) This is a course requirement; you can have more than one, but if they are outside of the UA (for example “hotmail.com”, you should remove spam blocking on messages from the listserve.)
Note: I need 3 to 5 people as group leaders who will earn up to 5 extra credit points. Send e-mail to sleavitt@ltrr.arizona.edu
Note: There are office hours in room 330 Space Sciences immediately before (11-12)
and immediately after (1-2) our class.
Turn off your cell phone!
Try your hand at
homework 1 on course web page, to see if you understand concepts of units,
scientific notation, conversions, graphs.
