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Monday, March 15, 2010

Apologia Science, Module 3, The Atmosphere

Interactive Study Links:
• Making flashcards at is a great way to study!  Create an account to be able save your flashcard sets to practice every day.  You can make cards for whatever you need to study in the chapter, not just vocabulary.  Here are some examples but be careful if you use these; some have had errors.  You will learn a lot more if you make your flashcards yourself.

Other Study Links:
Air Experiments at Science Matters.  Looks like most all these can be done with items around the house.  We are doing several from this website!
Top Ten Air Pressure Experiments at The Homeschool Mom
Egg/Balloon in a Bottle (Also see this Steve Spangler video illustration)
Layers of the Atmosphere - VERY good, concise explanation!  With links to visuals.
See these and more at Debbie's Educator's Resources.  (Thanks, Debbie!)

at·mos·phere  at'-mə-sfir n.
1. The gaseous mass or envelope surrounding a celestial body, especially the one surrounding the earth, and retained by the celestial body's gravitational field.
2. The air or climate in a specific place.
  • lithosphere - land
  • atmosphere - air
  • hydrosphere - water
  • biosphere - life

The ozone layer is in the stratosphere.
Most weather occurs in the troposphere.

(1) p. 57-61, Atmospheric Pressure

Sinking air gives us high pressure  and clears out the skies.
Low pressure allows the clouds to build up and you'll likely have weather.
►76 cm or 760 mm = 29.92 inches, which equals 1 atm.

What happens if there is NO Air Pressure!  Very fun video!

(2) p. 61b-62, The Layers of the Earth's Atmosphere

The atmosphere is made up of 2 main layers, which are further divided into more layers.
I.  Homosphere
     A.  Troposphere (0-11km)
          1. We live here.
          2. 78% nitrogen, 21% oxygen, 1% other gases
          3. Most weather occurs here.
     B.  Stratosphere (11-50km)
          1.  Jet stream
          2.  Ozone layer
     C.  Mesosphere (50-80km)
          1.  Meteor showers
II.  Heterosphere
     A.  Thermosphere
     B.  Exosphere

►Learn more about each layer here.        

To help you remember the difference between homosphere (even though as one goes higher, and the molecules are fewer, the percentage of gases is the same all the way up) and heterosphere (the mixtures are different at different levels)

(3) p. 63-66, The Homosphere

The layers of the Homosphere:
     Troposphere, Stratosphere, Mesosphere

►Another atmosphere video, this one showing scenes from when Joe Kittenger sky-jumped from over 19 miles from an air balloon!  That is way up in the stratosphere!

►It is very important to remember that the concentration of gases in the homosphere -- throughout the troposphere, the stratosphere, and the mesosphere -- changes at the same rate, the higher you go.
--A steady change like this is called a gradient.  
So the concentration gradient decreases with increasing altitude.
It is still 78% nitrogen, 21% oxygen, and 1% other, but it isn't as concentrated.  There are fewer and fewer molecules the higher you go.
Air pressure does the same -- decreases with increasing altitude.  You don't usually notice this unless you travel up or down a mountain or fly in a plane.  Then your ears might pop!

The temperature in the troposphere also decreases with increasing altitude, but in the stratosphere, this switches!  Then in the mesosphere, it switches back!
So the temperature gradient does not stay the same all the way up through the homosphere.

(4) p. 67-70a, What is Temperature?

(5) 70-71, The Temperature Gradient in the Homosphere

We learned that the concentration of gases that we breathe (nitrogen 78%, oxygen 21%, other 1%) changes at a steady rate from ground level all the way up through the three layers of the homosphere.  This steady rate is called a gradient.  More specifically, this is a concentration (of gases) gradient.
It is still 78% nitrogen, 21% oxygen, and 1% other, but it isn't as concentrated.  There are fewer and fewer molecules the higher you go.
It stays this way until it reaches the heterosphere, where there begins to be different kinds of gases at different levels.

The temperature changes in the homosphere also, and is called a temperature gradient.

The difference is that the temperature gradient (rate of change), changes with each layer.  Yes, a rate of change changes!
Through the lowest level of the homosphere (the troposphere), the temperature decreases as the altitude increases, just like the concentration gradient, and the pressure gradient.
But when you get to the stratosphere, the temperature gradient switches!  As the altitude increases in the stratosphere, the temperature increases.
When you get to the mesosphere, it switches back, once again decreasing as the altitude increases.

Why does this happen?
The ozone layer is in the stratosphere, and it absorbs the ultraviolet rays of the sun, and the energy of those rays.  So temperatures increase in this layer.

The temperature gradient within the troposphere gets colder the higher you go.

(6) p. 71-75a, The "Hole" in the Ozone Layer

I could find no videos for this section, so here are a few facts.

First, it isn't really a hole.  It is a thinning.
It is directly over Antarctica.
It occurs from August to sometime in November every year, caused by a weather phenomenon called the Polar Vortex.
After this period of time, the "hole" returns to normal thickness for the rest of the year.
Chlorofluorocarbons (CFCs) are completely non-toxic.
The ozone "hole" was discovered in 1956 before CFCs were being widely used.

(7) p. 75-76, The Heterosphere

Mysteries of the Sun: Ionosphere, Thermosphere, and Mesosphere from Science@NASA on Vimeo.


  1. Thank you for sharing all of these wonderful resources!!! We just started module 3 of Exploring Creation with Physical Science. I can't wait to use these resources for a better learning experience as we continue with this wonderful book. THANKS!!

  2. WOW! I am SO grateful for you sharing these videos and everything else you have shared here! This will be such an asset to our learning!

  3. Wow! Thank you SO much for all that you have shared here! I am so grateful!

  4. You're welcome, Nicole! =)
    Thank you for the comment. I love to hear from my readers. =)

  5. These videos really help me in my physical science class. Thanks! ;)

  6. Marty -- It is a few years since you posted these helpful hints/links/notes and they are still being used. Thank you. :)

  7. Thank you so much for making this available! Would you mind sharing how you graded? Did you use a sheet to keep track? I am still trying to figure out this whole grading thing:/

    1. I honestly don't remember... I probably either went by Apologia's grading system, or divided 100 by the number of problems on a quiz/test.
      When my "class" met for science experiments, etc, I had an oral quiz at then end, where I asked questions aloud, and they wrote on dry erase boards and showed me their answers. They got points and won candy.
      You can read more here
      and here


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