A HINT OF ADIABATICS – IT’S A GAS!

Friday, 11-21-2008

Several years ago this bag of corn chips was purchased somewhere in Southern California.  Shortly afterwards one of my two former students hiking the Mt. Whitney trail with me pulled it out of his backpack when we were taking a break at the 11,395′ benchmark near Consultation Lake.  Adam and Carl were game hikers and a joy to be with.  I’ve lost track of Adam but Carl (Opper) is an earth science professor at St. Petersburg College.  He makes me proud.

I must admit that right now I have a problem with this image:

IT ACCURATELY DEPICTS

HOW MY ABDOMEN FEELS THIS EVENING!

That strange statement will be explained in a moment.

Of course the reason why the bag is near bursting is because the atmospheric pressure upon it is so much less than it was where it was packaged and sealed.  The image also illustrates that when air rises, it expands.  Interestingly, the “heat” within the air inside the bag is spread out over a greater volume due to the expansion.  Therefore, were it measured, one would find the temperature of the air at any point inside the bag to be colder than it was at the beginning of the hike.  But, the amount of heat inside the bag would be essentially the same as at the beginning of the hike, except for the small amount lost due to radiation cooling of the bag’s surface.

Did you catch that?  When air rises and expands the temperature changes but the amount of heat remains essentially the same.  I was reminded many times during my years of teaching that many people do not discriminate between the word, heat and the word, temperature.  The fact is, they do not mean the same thing.  For example, it takes a lot more heat to increase a gallon of room temperature water up to boiling than to increase a quart of room temperature water up to boiling – though the temperatures of each once the heating was accomplished would be the same at boiling.

When unsaturated air rises, its temperature drops at a rate of about 1degree C. per 100 meters of ascent!  When saturated air rises its temperature drops at a rate of about 0.6 degrees C. per 100 meters.  The reduction (retardation) is due to the fact that when saturated air is rising and being further cooled by expansion – condensation occurs which releases heat; the heat released slows down the rate of expansion cooling.

This is the crux of adiabatic cooling, a subject which will come up sooner or later at this site (as well as adiabatic heating).  NOW: Back to the strange comment about my abdomen.

Even before we returned to our Florida home from our month-long stay at our mountain cabin I knew that something inside my lower abdomen was not quite right.  After getting back to Florida I investigated on-line and correctly reached the conclusion that I had a hernia.  The surgeon found a second one when he examined me.  I had surgery that took a little over two hours early in the afternoon on Monday.  The surgeon found a third hernia while he was in there looking around with his magic wand, the laparoscope.

All went well.  The surgery was done on an out-patient basis.  That’s not a complaint.  Once my head hit the pillow at home I felt very tired but I was not sleepy!  I was so relieved that I jabbered off and on all night long.  My poor wife!  Perhaps the medication played a role in that.

The surgery is the main reason for my inactivity on line – that plus the fact that there is no tropical weather going on right now, being near the end of the official season.  I’ve read that it’s over but my feeling always at this time of year is, “It ain’t over ’til it’s over!” spoken first (I think) by the great living sage, Yogi Berra.  Out-of- season storms have occurred though such events are relatively rare.  Here are two examples:

1) Hurricane Alice formed at 1 A.M. EST December 30, 1954 and continued as a hurricane into January 6, 1955.  Here’s a plot.

http://www.stormpulse.com/hurricane-alice-1954

2) A hurricane formed on March 6, 1908.  It is called both “The March, 1908 Hurricane” and “1908 Hurricane #1.”  Here’s a plot.

http://weather.unisys.com/hurricane/atlantic/1908/1/track.gif

IF THIS IS THE ONLY POST YOU SEE –

AND YOU WOULD LIKE TO SEE OTHERS,

PLEASE CLICK ON THE BLOG TAB ABOVE.

« Link to Prognostic Loop for North America

Tornado Watch – Much of Florida »