since the upper atmosphere was not even thought to exist, it was quite a problem to explain the observations. It was not until the Space Age allowed us to measure the thermal structure of the atmosphere that much progress was made in explaining tides in the atmosphere in any detail. The infamous V-2 rocket, taken as a spoil of World War II, was outfitted with a thermometer and launched over the New Mexico desert. Now we know that it gets cold on a mountaintop, and one might guess this trend would continue. But no, it turns out that the temperature begins to rise again due to absorption of UV light by the ozone layer. This discovery changed everything for theorists studying atmospheric tides. They were finally able to show that solar heating dominates atmospheric tides, as opposed to the well-established dominant role of the Moon and the Sun's gravitational pull on the oceans. A very interesting work by Sydney Chapman and R.S. Lindzen (see reading list) explains the history of tidal theory, including the dominant influence of Lord Kelvin, who espoused an incorrect theory with such authority that it was accepted for decades. The first hint about upward-traveling waves came out of tidal theory, and the regular pattern of magnetic fluctuations began to be understood. Electric currents must be flowing in space, driven by tidal surges. Space weather exists.

During the spectacular Leonids meteor shower of 1866, and possibly the equally bountiful one of 1833, strange distortions of meteor contrails were seen. The sketch in Figure 4 was drawn by an observer in Cardiff, England, for an event on November 14, 1866, an event that was visible for 10 minutes (Trowbridge, 1907). Illustrations were published and analyzed, but again, the explanations were not easy. At the time the atmosphere was not known to extend as high as the observations indicated, let alone thought to have internal wave activity. Such long-lived trails are very rare except during showers. Indeed, during the November 1996 Leonids shower the author observed five such displays, one lasting several minutes.

Buoyancy waves were first detected in the aftermath of the great volcanic explosion of Krakatau in 1885. This was indeed the first blast heard round the world, at least by instruments. Once the reports

FIGURE 4 Meteor contrails distorted by atmospheric waves. Reproduced from Trowbridge (1907), p. 395, with permission of the American Meteorological Society.



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