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Monday, April 5, 2010

Apologia Physical Science, Module 5, The Hydrosphere

Interactive Study Links
• Create an account and make your own flashcards at!

Other Study Links
Simulating the Water Cycle - in place of Exp. 5.1, my class will be doing this one at home.
Hydrogen Bonding Property of Ice
See these and more at Debbie's Educator's Resources.  (Thanks, Debbie!)

hy·dro·sphere hi'-drə-sfir n.
1. The waters of the earth's surface as distinguished from those of the lithosphere and the atmosphere.
2. The water vapor in the earth's atmosphere.
  • lithosphere - land
  • atmosphere - air
  • hydrosphere - water
  • biosphere - life

(1) p. 105-106, Introduction
-Hydrosphere:  the sum total of all water on a planet  
(Do not confuse this word with homosphere or heterosphere, which are layers of the atmosphere.) 
Earth System Science - from NASA

(2) p. 107-113, The Parts of the Hydrosphere and the Hydrologic Cycle


Evaporation and Condensation

Hydrologic Cycle

Haha!  "Son, it's time to join the hydrologic cycle."

(3) p. 114-116, The Ocean

What could one do if they were in a place that only had undrinkable saltwater?
Watch this video to find out.

This experiment looks so interesting!
I can see that one glass has "high salinity" written on the label, so I'm assuming the other is low/no salinity. What I don't know is if either of the glasses hold warm or cool water, and what kind of water is in the dish.
It would be a true experiment to try different combinations, being sure to change only one variable at a time.

What do different measures of salinity or of temperature have to do with ocean currents?
Watch this video to find out.

(4) p. 116b-120, Glaciers and Icebergs

►See image: tip of the iceberg

• What is the difference between glaciers and icebergs?
• Are they made of freshwater or saltwater?
• What is sea ice?

Every iceberg starts as a glacier.
Since the temperature decreases the higher you go, many mountains in the troposphere contain snow year round.  The weight of new snow each year keeps packing down the snow under it,  and the snow at the bottom becomes dense and icy.  That hard layer is called a firn.  (like firm!)  This is how glaciers are formed.
Glaciers eventually slide down the mountain (slowly), and as they get to warmer areas, they will begin to melt and contribute to many freshwater sources.
But in polar regions, there are no warm areas, so glaciers will not melt.  When they slide all the way down, they project out into the sea, making an ice shelf.  Eventually they can move out into the sea far enough to float.  When large chunks of ice break away from a glacier, they are called icebergs.  This breaking away is sometimes referred to as "calving" like a cow having a baby!

So... since glaciers and icebergs are originally made from snow, if a piece was melted would it be freshwater or saltwater?
Hint:  Snow falls from the sky... And when water evaporates from anywhere on earth, including from the ocean, salt does not evaporate with it.  (It would need to be at least 800º Celcius for that to happen!  According to Kyle's Converter, that is 1,472º F!!!)
Per an email from Apologia:
"Salt doesn't evaporate from the ocean because there isn't enough energy to allow that to happen. In order to evaporate, a given molecule needs a certain amount of energy. The energy needed for water to evaporate is available at room temperature. However, since the ions in salt are so strongly attracted to each other, it takes a LOT more energy to evaporate salt. That energy begins to be available at about 800 degrees Celsius. Thus, salt cannot evaporate at the temperatures the ocean experiences near its surface."

Sea ice on the other hand is different than glaciers and icebergs.
Sea ice is frozen ocean water.
As ice freezes, it ceases to hydrogen bond.  But it is still "stuck" together in a frozen state.  And as it freezes, salt molecules get trapped inside the ice.  So it isn't frozen saltwater, since the molecules of salt are no longer "dissolved."  However, if you melted a chunk of sea ice, the salt and water would re-dissolve as it melted.
Interesting note:  Water begins to expand at 39.2º.  So it doesn't wait until it is at its freezing point.  It would be strange if it suddenly expanded right at freezing.

(5) p. 120b-122a, Groundwater and Soil Moisture

The amount of water on the earth today is the same amount as it has been for thousands of years.
Water is cycled over and over.  Water cannot "grow" from a source.  It comes from the ground or sky, but it got there from going through different processes of the hydrologic cycle.
Sometimes there is a drought in certain areas, and the people living in those areas need to be very careful for awhile with the amounts of water they use.

(6) p. 122-123a, Surface Water

Sources of freshwater:
  • icebergs
  • glaciers
  • groundwater
  • lakes
  • rivers
  • ponds
  • streams
But not all ponds and lakes are sources of freshwater.

(7) p. 123-126, Atmospheric Moisture

►Video - How Clouds Form

Making a Cloud in a Bottle  Vapor attaches to tiny smoke particles, just as vapor attaches to particles in the atmosphere to form clouds.  When heated, liquids usually expand and become a gas.  But adiabatic cooling is cooling (not heating) of a gas when that gas expands.  The cooling caused some of the water vapor in the bottle to condense on the smoke particles.  This made the cloud.

►Another video if you want to watch it.

How Weather Occurs - from NASA

Good to watch this again after learning about clouds in Module 7.

Satellite Image Time Lapse of Cloud Movement
From September 23 - October 16, 2005.  The dates are in the corner.  Watch the clouds swirl as they are moved about by the Coriolis effect as the earth rotates (module 7), and as they are pushed by weather fronts.

(8) p. 126b-127, Water Pollution

I didn't find a good video for this section.


  1. the earth system science vid doesnt work

    1. Hmmm... it works for me, but I'm viewing on a computer. Are you viewing from a different device? Not sure if that would affect it or not...


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