Friday, February 15, 2013

Notes – February 15, 2013

Lot to be thankful for this Valentine’s week:
...My sweetheart of a wife...with whom I have shared many good adventures all these years. 
...My sons, neighbors, relatives, colleagues, friends, and people remembered.
...My successful surgery a month ago today... and the gradual return of stamina.
...Signs of swelling buds and new sprouts – spring can not be far away... (But, oh, a little more rain would be welcome!)
...The asteroid that flew past us today did not hit us!  (The meteorite that struck Siberia had no relationship to the asteroid):

Antique Valentine

By mid February I expect morning frost to be pretty well over - but still each morning, on my way out to pick up the morning newspaper I check the roofs of parked cars...  The evening dew undergoes an amazing transformation each frosty night!  As water cools the molecules slow their motion and the liquid water first becomes more tightly packed, and then change their crystalline pattern as they freeze.  For a gram of liquid water to freeze, 80 physics calories of heat must be given off to permit the physical change to take place.  If the air is cold enough the heat is easily carried away.  (1 teaspoon of water  = 5 grams)  (1000 physics calories = 1 food calorie)
Water Molecule diagram - Covalent bonds involves both atoms attracted to the same electrons

Each water molecule has two hydrogen atoms and one oxygen... The two hydrogen atoms are somewhat closer together at one end of the molecule.  Each water molecule is like a little weak magnet.  The  oxygen end is more positive in charge and the hydrogen end more negative.  In normal liquid water the molecules are drawn together or repulsed due to the weak interaction of the + and – charges...  But the attractions are weak and easily break and re-form in liquid water.  The electrical charges in the water molecules explain why a droplet of liquid water develops the surface tension that causes water drops to form little spheres ... like rain drops and drops from a faucet.  The positive and negative forces of the water molecules are pulling the molecules together into the most compact volume possible.

Surface tension in water is caused by the strong magnetic attraction between individual water molecules

Just before freezing the water molecules undergo a dramatic change.  When water cools down to form ice, the motion of the molecules continues to slows down.  At 4°C (39 °F) liquid water reaches it greatest density, but then if further cooled the bonding pattern of the water molecules changes in away that causes the over all density to become less than liquid water. The molecules begin to form into 6 sided crystals of ice as the freezing point is reached. 

Liquid water involves separate water molecules forming and reforming temporary hydrogen bonds with other water molecules.
This ice field in August has not yet collected enough summer heat to convert the ice crystals of winter into liquid water.
Because normal  water becomes more dense at it cools down, colder water is found at the bottom of a lake or ocean.  But once it starts to become more crystalline as ice forms, the ice is less dense that normal liquid water – and the ice forms on top of the liquid water. If ice was more dense that liquid water lakes and oceans would be frozen solid at lower depths and only the top-most  portion would thaw in the summertime.

Ice floats because it is less dense than liquid water

The frost patterns that I see formed on the cars and plants are due to the positive and negative attractions and repulsions between the chilled water molecules.  if I look closely I can see the same recurring angles and patterns in the ice caused by the 6 sided ice crystals.  ( Think of snow flakes. ) When the sun rises and there is adequate  heat energy to change ice back into liquid water, these bonds will break and the 6 sides molecules will break down to form free molecules again.

Ice crystals the world over form the same predictable angles and patterns - but in an infinite variety of specific arrangements.

How wonderful to think that this whole grand system of ice crystal frost structures that formed in the night will all be transformed with the addition the first morning sunlight providing heat. All this great complexity of detail will be gone in a few moments time.   No water molecules are created or destroyed in the process – Just the addition or withdrawal of heat energy causes the ice to form or disappear. 
Theoretical construct of how the water molecules combine together when ice molecules are formed.

And what about the energy of the sun – is it created or destroyed...?  Massive thermo-nuclear reactions on the sun force H atoms to combine into Helium atoms – releasing huge energy content.... Some small part of that is captured on the revolving earth,  and absorbed by the  soil, rocks and water – and then dissipated back into the blackness of space at night... Where  does that energy go?  Is there a unified  process to recycle or return the lost energy into a reverse of the “Big Bang”?  - I somehow find it comforting to think that there are areas for which we have no knowledge – no clue... The frontier of mystery always keeps beckoning.

All snow flakes are based on 6 sided ice crystals - since there are an infinite number of ways for the water molecules to combine to form the crystals we can safely assume that truly no two snow flakes can be identical.

So the conversion of liquid water to ice is an example of a conceptual model - The details of the process are not something that can be objectively seen but each step has been verified and confirmed by laboratory evidence and measurements.  Its a good example of a scientific theory.  Does that make it unreliable? No!  There are many processes in nature that can not be directly observable that have overwhelming evidence in their support.  In the nature of science this is not a dogma but an idea always open to further investigation and conclusions - its just that all evidence points to this interpretation and no better interpretations have been offered. If a better interpretation could be developed and confirmed by experimentation the scientific community would welcome that new idea. Scientific ideas are always open to reinterpretation.


SOCIAL COMMENTARY OF THE WEEK: Source: Huffington Post,  International Labor Organization
Why are we so stingy in our support of maternity leave?

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