Tuesday, December 28, 2004

Atmospheric Physics Part IV

The enormous amount of energy released in the earthquake and resultant tsunami off Sumatra dwarfs the efforts of Man. It truly raises the question, can Man really affect the environment in the face of the power of Nature? Are we capable of changing the climate through global warming? Let’s do some calculations.

One common unit of measure in these exalted realms is the kiloton equivalent of TNT (KT). This is given as 4,000,000,000,000 joules. Using the conversion factor of 1 British Thermal Unit (BTU) is equal to 1,055 joules, we come to the result that 1 KT = 3,790,000,000 BTUs.

Now let us consider a volume of air one mile on a side (i.e. 1 cubic mile). Using this calculator to figure the pressure at one mile (5280 feet) with a sea level pressure of 14.7 psi and a temperaure of 27 degrees C, we arrive at a pressure of 12.24 psi @ 5280 feet. So a column of air one mile high and one square inch in area horizontally weights 14.7 – 12.24 = 2.46 pounds. Multiplying by 144 square inches per square foot, then by 5280 times 5280 (feet/mile) we arrive at a total mass of 9,875,644,416 pounds for one cubic mile of air starting at sea level up.
The heat required to raise the temperature of that mass just one degree F, is equal to the mass times the specific heat (.24 BTU/pound – degree F). Doing the math we find that it takes about 2,370,000,000 BTUs to raise the temperature a single degree. That is 0.625 KT energy equivalent. I assume you all have seen the air temperature rise 20 degrees from morning to mid-afternoon. That would work out to be 12.5 KT or an amount equal to the atomic bomb at Hiroshima. Chicago has an area of 89 square miles. So heating just the lower mile of the atmosphere takes over 1 Megaton (MT) equivalent of energy. The Sun drops The Bomb on Chicago every summer day! Man is quite puny in the face of Nature, as was proven yesterday.


Blogger Timothy Birdnow said...

Great post! I reprinted it on my own blog for all 2 of my fans to see! Talk about super service-I asked for another Atmospheric Physics and I received!

6:42 PM  

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