Prior to the space age, meteorologists rarely paid particular attention to the height regions above the tropopause. What was known about the upper atmosphere above about 100 km came essentially from ionospheric and geomagnetic research. The region in between, presently known as the middle atmosphere, was almost terra incognita above the height reachable by balloons. It was space research that allowed for the first time direct access to middle and upper atmospheric heights. About 40 years ago, Sidney Chapman coined a new word ''aeronomy'' to describe the study of these two height regions. When asked about the difference between aeronomy and meteorology, he allegedly replied: ''it is the same as between astronomy and astrology'' . This mild irony indicates the preferred prejudice of many ionospheric physicists and geomagneticians in those days toward meteorology as a descriptive rather than an exact science, in spite of the presence of such giants as Carl Rossby and Hans Ertel.
