Subject: Loop of the Week

Posted by Bill Barroway on 11/6/2003
In Reply To:Loop of the Week Posted by John Sterman on 11/5/2003

Message:

Figure 4.1 of the following URL can put the water cycle within a bigger global context. It is an integrated model of the Earth system for decadal climate prediction

http://www.earth.nasa.gov/visions/historical/draftsciplan/section4.htm

Basically evaporation of water from the ocean DOES effect the ocean, not so much from loss of water, but from cooling the surface, which does in turn effect the rate of evaporation. An improved model of the water cycle includes not just matter (water), but also kinetic, themal, radiative, and potential energies. Add in winds and currents (and coriolis effects) mixing matter and energy both horizontally and vertically in both the oceans and the atmosphere, and the whole thing becomes pretty complex. Fig 4.1 is a gross level systems diagram that maps out the major elements for our climate. The URL for the diagram alone is below:

http://www.earth.nasa.gov/visions/historical/draftsciplan/fig4-1.gif

(The reason for my interest in this is a past life doing laboratory physics in support of atmospheric studies.)

So what's the point? Modeling is often a process of moving from simplicity and approximation to complexity and greater accuracy. This certainly seems true for climate studies. The history of models of the atom also provides a nice example of this movement in the development of physics knowledge. IMHO, what a text of the water cycle provides is an opportunity to engage children in a learning process with materials that (at least the author thinks) are developmentally appropriate. If the child can come to understand that the text simplifies in its presentation, then that understanding can arguable be considered a smoking gun that a "teachable moment" has happened.

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