Wednesday Jan. 13, 2016

A couple of songs from Lissie:
"Record Collector" (4:14) (recorded in the studios of KCMP FM, Minnesota Public Radio), and "In Sleep" (5:23) part of a set at the end of the Guitar Center's Singer/Songwriter 2 Competition Finals at Hotel Café in Hollywood (Mar., 2013) to check out the audio system in ILC 150.
Several more songs from the same artist are included below.

"They All Want You" (4:14), and "Further Away" (4:14) from the Bing Lounge at 101.9 KINK FM (Portland, OR).
"Love in the City" (3:46), "The Habit" Live at Hotel San Jose, SXSW 2013 (4:26)

Today's lecture notes are shown below.


Information about this class and course requirements
ATMO 170 is off and running once again.  We first briefly discussed the Course Information handout.  Please read through that information carefully on your own and let me know if you have any questions or concerns.

A textbook is not required for this class.  If you want a different and more complete picture of the subject, you might want to purchase one of the textbooks that are being used in the other ATMO 170A1 sections.  Or if you'd like to borrow one of the instructor copies of introductory level textbooks that I have in my office, just let me know.  Otherwise you should be able to do perfectly well in the class by reading the online notes.  And you should read the online notes even if you are in class.

A set of photocopied ClassNotes (available in the ASUA Bookstore in the Student Union) is "required."  You should try to purchase a copy as soon as you can because we may well be using them in class on Friday.  If you know someone with notes leftover from the Fall or Spring 2015 semesters they will work fine.

Writing is an important part of this class and is described in more detail on the Writing Requirements handout Please have a careful look at that also and let me know if you have any questions.

The first half of your writing grade is an experiment report.  You only need to do one of the experiments, so think about which of the experiments (listed on the handout) you might like to do.  I'll bring a signup sheet to class on Friday.  I'm also planning on bringing about 40 sets of Experiment #1 materials to class on Friday for checkout.  Checkout is first come first served.  Materials for the other experiments will be handed out at roughly 3-week intervals.


The so-called One Side of One Page (1S1P) reports make up the second part of your writing grade.  Topics will appear periodically during the semester on the class webpage.  As you write reports you will earn points (the exact number of points will depend on the topic and the quality of your report).  Your goal should be to earn 45 1S1P pts, the maximum number allowed, by the end of the semester.

You'll be allowed to revise and raise your grade on the first draft of your experiment report.  So you should be able to earn a pretty high score on that.  And, unless you procrastinate, you can just keep on writing 1S1P reports until you've earned 45 points.  There's no reason not to earn a high writing grade.  The writing grade gets averaged in with your quiz scores and, as the example below shows, can have a significant and beneficial effect on your overall grade.



Grade example

Your final grade in this class will depend on your quiz scores, how much extra credit you earn (from optional take home and in class assignments), your writing grade, and (perhaps) your score on the final exam.  A sample grade report from one of the Fall 2015 sections of this class is shown below (most of the numbers are class averages).


Doe_J
quiz1 -42 (170 pts possible) 75.3%   quiz scores
quiz2 -51 (175 pts possible) 72.9%
quiz3 -47 (175 pts possible) 73.1%
quiz4 -52 (175 pts possible) 70.3%

2.5 EC points (3.3 pts possible)      extra credit earned on optional assignments

writing scores
writing scores: 32.0 (expt/book report) + 45.0 (1S1P pts)
writing grade: 96.3%

overall averages (prior to the Final Exam)
average (no quiz scores dropped): 77.6% + 2.5 = 80.0%    
average (lowest quiz score dropped): 79.4% + 2.5 = 81.9%

Final exam score: 76.0%    


Overall grade: 80.7% (B)

The 4 quiz grades are shown at the top.

S
tudents that did turn in the Optional Assignments earned on average 2.5 pts of extra credit during the semester.  You will have the opportunity to earn at least 3 extra credit points. 

A score of 32 points (out of 40) on the experiment report and 45 1S1P points resulted in a writing percentage grade of 96.3%.  There's no good reason not to end up with a writing score close to 100% (or even greater than 100%)


The overall average without any quiz scores dropped is shown next.  Since the result, 80.0%, is less than 90.0% the average student last fall did have to take the final exam  The second average (with the lowest score dropped) is a little higher, 81.9%.

If you do well on the final exam it will count 40% of your overall grade (trying to maximize the benefit it can have).  If you don't do so well on the final it only counts 20% (minimizing the damage it can cause).  In this example the final exam score (76%) was lower than the 81.9% value, so the final exam only counted 20% and the overall score was 80.7%. 

Be sure to note that even with C grades on each of the quizzes and a C on the Final Exam you could well end up with a B in the class.  That is possible when you have a high writing grade and also have some extra credit points.



"Chapter 1" - the earth's atmosphere
We did cover a little course material on this first day of class so that you can get an idea of how that will work.  Also I won't feel so bad about not covering new material on the last day of class in May.

If we were using a book we'd start in Chapter 1 and here's some of what we would first be looking at in this course. 


We will come back to the first item, the composition of the atmosphere, today.

Before we do that however, here are a few questions to get you thinking about the air around you.  We didn't really cover any of this in class.

Can we see air?



Air is mostly clear, transparent, and invisible.  Most gases are invisible.  Sometimes the air looks foggy, hazy, or smoggy.  In those cases you are probably "seeing" small water droplets or ice crystals (fog) or small particles of dust or smoke (haze and smog).  The particles themselves may be too small to be seen with the naked eye but are visible because they scatter (redirect) light.  I didn't really mention or explain what that is but it's a pretty important concept and we will learn more about it soon.

And to be completely honest air isn't really invisible.  If you shine a bright light through enough air, such as when sunlight shines through the atmosphere, the air (the sky) appears blue.  This is a little more complicated form of scattering of sunlight by air molecules.  We'll come back to this later as well.


Can you smell air?



I don't think you can smell or taste air (air containing nitrogen, oxygen, water vapor, argon and carbon dioxide).  But t
here are also lots of other odors you can sometimes smell (freshly cut grass, hamburgers on a grill, etc).  I don't consider these normal constituents of the atmosphere.  You can probably also smell certain pollutants.  I suspect our sense of smell is sensitive enough for us to detect certain air pollutants even when their concentration is very small (probably a good thing because many of them are poisonous). 

Natural gas (methane) used in hot water heaters, some stoves, and furnaces is odorless.  A chemical (mercaptan) is added to natural gas so that you can smell it and know when there is a leak before it builds up to a concentration that could cause an explosion. 

Can you feel air


It is harder to answer this question.  We're always in contact with air.  Maybe we've grown so accustomed to it we aren't aware of how it feels.  We can certainly feel whether the air is hot or cold, but that have more to do with energy exchange between us and our surroundings.  And we can feel wind. 

In a couple of weeks we will see that, here in the classroom, air pressure is pressing on every square inch of our bodies with 12 or 13 pounds of force.  If that were to change suddenly I'm pretty sure we'd feel it and it would probably really hurt.


2 objectives for today:

1. You should be able to list the 5 most abundant gases in air and say something (maybe more than one thing) about each of them

2. You should be able to define or explain dew point temperature and you should know the meaning of the term monsoon.

Let's start with the most abundant gas in the atmosphere.  I poured some of that material (in liquid form) into a Styrofoam cup.  Here's a photo I took back in my office.






You can see the liquid, it's clear, it looks like water.  Probably a lot of you knew this was nitrogen.  Liquid nitrogen is very cold and begins to boil (evaporate) at -321o F.

The most abundant gas in the earth's atmosphere is nitrogen.  We'll use liquid nitrogen in several class demonstration this semester mostly because it is so cold. 

Nitrogen was discovered in 1772 by Daniel Rutherford (a Scottish botanist).  Atmospheric nitrogen is relatively unreactive and is sometimes used to replace air in packaged foods to preserve freshness.  You don't need to worry about details like this for a quiz.

Oxygen is the second most abundant gas in the atmosphere.  Oxygen is the most abundant element (by mass) in the earth's crust, in ocean water, and in the human body.  In liquid form it also becomes visible.









from: http://www.webelements.com/oxygen/
The web elements site credits Prof. James Marshall's Walking Tour of the Elements.
from: http://en.wikipedia.org/wiki/Oxygen
Wikipedia credits Dr. Warwick Hillier of Australia National University
A nice picture of liquid oxygen's pale blue color from this source.


Some photographs of liquid oxygen (O2) are shown above (it boils at -297o F).  It has a (very faint) pale blue color (I was pretty disappointed when I first saw it because I had heard it was blue and imagined it was a deeper more vivid blue).    When heated (such as in an automobile engine) the oxygen and nitrogen in air react to form compounds such as nitric oxide (NO), nitrogen dioxide (NO2), and nitrous oxide (N2O).  Together as a group these are called oxides of nitrogen; the first two are air pollutants, the last is a greenhouse gas.  I'd love to bring some liquid oxygen to class but I'm not sure it's available on campus and you probably need to be careful with it because it is reactive.

I recently learned that liquid ozone (
O3) does have a nice deep blue color. 


Liquid ozone (source of this photograph).

It's probably very hard to find and is also very (dangerously) reactive.  Ozone gas is also poisonous.

Here is a complete list of the 5 most abundant gases in air.  And a note about the figures you'll find in these online notes.  They may differ somewhat from those drawn in class.  I often redraw them after class, or use neater versions from a previous semester for improved clarity (and so I can get the notes online more quickly).  





With a little practice you should be able to start with a blank sheet of paper and reproduce the list below.

Water vapor and argon are the 3rd and 4th most abundant gases in the atmosphere.  A 2% water vapor concentration is listed above but it can vary from near 0% to as high as 3% or 4%.  Water vapor is, in many locations, the 3rd most abundant gas in air.  In Tucson most of the year, the air is dry enough that argon is in 3rd position and water vapor is 4th.
   Water vapor and carbon dioxide are circled because they are greenhouse gases.

Water vapor, a gas, is invisible.   Water is the only compound that exists naturally in solid, liquid, and gaseous phases in the atmosphere.

Argon is an unreactive noble gas (helium, neon, krypton, xenon, and radon are also inert gases).



Here's a picture of solid argon ("argon ice").  It melts at melts at -309o F and boils at -302o F; it's doing both in this picture. (image source).

Here's a little more explanation (from Wikipedia) of why noble gases are so unreactive.  You can gloss over all these additional details if you want to, none of this was covered in class.  The noble gases have full valence electron shells.  Valence electrons are the outermost electrons of an atom and are normally the only electrons that participate in chemical bonding.   Atoms with full valence electron shells are extremely stable and therefore do not tend to form chemical bonds and have little tendency to gain or lose electrons (take electrons from or give electrons to atoms of different materials).







Noble gases are often used used in "neon signs"; argon produces a blue color.  The colors produced by Argon (Ar), Helium (He), Kryton (Kr), Neon (Ne) and Xenon (Xe), which are also noble gases, are shown above (source of the images).   An electric current is traveling through and heating the gas in the tube causing it to emit light.  You're seeing the light emitted by the gas itself.  The inert gases don't react with the metal electrodes in the bulbs. 

Fluorescent bulbs (including energy saving CFLs) often also contain mercury vapor (which means you should properly dispose of them when they burn out).  The mercury vapor in CFL bulbs emits ultraviolet light that strikes a phosphor coating on the inside of the bulb.  Different colors are emitted depending on the particular type of phosphor used in the bulb.





This is solid carbon dioxide, better known as dry ice.  It doesn't melt, it sublimes.  Sublimation is a solid to gas phase change, evaporation is a liquid to gas change.  (source of the image above).

The concentration of carbon dioxide in air is much smaller than the other gases (it's about 0.04% but you don't need to remember the actual value).  That doesn't mean it isn't important.  We'll spend a lot of time this semester talking about water vapor and also carbon dioxide.  Water vapor and carbon dioxide are the two best known and most important greenhouse gases.  The greenhouse effect warms the earth.  Concentrations of greenhouse gases such as carbon dioxide are increasing and there is concern this will strengthen the greenhouse effect and cause global warming.  That's a topic we'll look at during the semester.



If we were using a textbook we'd probably find something like the following table near the beginning of the book ( I found this table a few years ago in a Wikipedia article about the earth's atmosphere ).

Composition of dry atmosphere, by volume
ppmv: parts per million by volume (note: volume fraction is equal to mole fraction for ideal gas only, see volume (thermodynamics))
Gas Volume
Nitrogen (N2) 780,840 ppmv (78.084%)
Oxygen (O2) 209,460 ppmv (20.946%)
Argon (Ar) 9,340 ppmv (0.9340%)
Carbon dioxide (CO2) 394.45 ppmv (0.039445%)
Neon (Ne) 18.18 ppmv (0.001818%)
Helium (He) 5.24 ppmv (0.000524%)
Methane (CH4) 1.79 ppmv (0.000179%)
Krypton (Kr) 1.14 ppmv (0.000114%)
Hydrogen (H2) 0.55 ppmv (0.000055%)
Nitrous oxide (N2O) 0.325 ppmv (0.0000325%)
Carbon monoxide (CO) 0.1 ppmv (0.00001%)
Xenon (Xe) 0.09 ppmv (9×10−6%) (0.000009%)
Ozone (O3) 0.0 to 0.07 ppmv (0 to 7×10−6%)
Nitrogen dioxide (NO2) 0.02 ppmv (2×10−6%) (0.000002%)
Iodine (I2) 0.01 ppmv (1×10−6%) (0.000001%)
Ammonia (NH3) trace
Not included in list above (dry atmosphere):
Water vapor (H2O) ~0.40% over full atmosphere, typically 1%-4% at surface


I like our list of the 5 most abundant gases better.  It's much more manageable.  There is almost too much information in a chart like this, you might be overwhelmed and not remember much.  Also unless you are familiar with the units on the numbers they might be confusing.  And notice you don't find water vapor in 3rd or 4th position near the top of the chart.  That's because this is a list of the gases in dry air.  Unless you're very attentive, you might miss that fact and might not see water vapor way which is included at the bottom of the chart. 

If you click on the link above to the Wikipedia article on the earth's atmosphere, you'll find that the list above has been replaced with a shorter simpler list (much more like the one we created in class).



Dew point temperature and the summer monsoon

Water plays many important roles in the atmosphere.  One of them is the formation of clouds, storms, and precipitation.  Meteorologists are very interested in knowing and keeping track of how much water vapor is in the air.  One of the variables they use is the dew point temperature.  The value of the dew point gives you an idea of how much water vapor is actually in the air.  A high dew point value means a higher the water vapor concentration.





The chart below gives a rough equivalence between dew point temperature and percentage concentration of water vapor in the air.


Note that for every 20 F increase in dew point temperature, the amount of water vapor in the air roughly doubles. 

Air temperature will always be equal to or warmer than the dew point temperature.  Experiencing 80o F dew points would be very unpleasant and possibly life threatening because your body might not be able to cool itself ( the air temperature would probably be in the 90s or maybe even warmer). 
You could get heatstroke and die.


Click here to see current dew point temperatures across the U.S.  Here's a link concerning unusually high, even record setting dew point temperatures. 

This is as far as we got today in class.  I've moved material on the summer monsoon and the dew point's "2nd job" to the start of the Fri., Jan. 15 classnotes.