[Images: Via Peter Moore?s piece on ?dueling weathermen? over at Nautilus]. As mentioned in the previous post, I recently had the pleasure of reading Peter Moore?s new book, The Weather Experiment. There are many interesting things in it?including the London ?time ball,? of course?but one scene in particular stood out for its odd design details.
In 19th-century Philadelphia, Moore explains, climate scientist James Espy began building a miniature model of the earth?s atmosphere in his back garden on Chestnut Street. This microcosm was a nephelescope, or ?an air pump attached to a barometer and a tubular vessel?something of an early cloud chamber.?
Espy?s larger goal here was to understand the sky as a complexly marbled world of colliding fronts and rising air columns, ?an entire dynamic weather system? that could perhaps best be studied through replication. The sky, that is, could be modeled?and, if correctly modeled, predicted. It was just a question of understanding the physics of ?ascending currents of warm air drawing up vapor, the vapor condensing at a specific height, expanding and forming clouds, and then the water droplets falling back to earth.?Under different atmospheric conditions, Espy realized, this system of vaporous circulation was capable of producing every type of precipitation: rain, snow, or hail. His task then became to calculate specific circumstances. What temperature was needed to produce snow" What expansion of water vapor would produce wo...