Saturday, November 07, 2009

An interesting metaphor

Two waterspouts
Image source: Weatherblog

Stephen Johnson begins his book, The Invention of Air, with a description of Joseph Priestly's voyage to the United States in 1794 which included the simultaneous sighting of four waterspouts. Later he uses the waterspout as a metaphor for the conservative riot in Birmingham that destroyed Unitarian meeting houses and the home of the Priestly family.

It occurred to me that the metaphor might be extended. The ocean and the atmosphere exhibit changes at different time scales. Ocean temperatures change slowly while atmospheric temperatures change rapidly; ocean currents move huge masses but do so slowly while atmospheric currents move gases much more rapidly. We can feel and see the atmospheric changes, at least locally, and we can see changes at the surface of the sea, but the deeper changes of the ocean are "beneath the surface". If you want to understand weather and climate you have to understand the oceans and the oceanic-atmospheric interactions.

Can this system be used as a metaphor for history, in which there are often unseen undercurrents that have long term effects, visible and invisible atmospheric changes, all of which result in the weather of day to day events including showers, storms and even hurricanes? If so, perhaps historians too often attend to the tempest and not to the climate.

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