Supplemental reading:

Lorenz (1967)

Palmén and Newton (1967)

Charney (1973)

General remarks

Our introduction to the observed state of motion and temperature in the atmosphere will be restricted (for the most part) to fairly gross features. Almost no mention will be made of the numerous features most closely associated with the most common perceptions of weather: hurricanes, fronts, thunderstorms, tornadoes, and clear air turbulence, to name a few. While there is something perhaps paradoxical and certainly regrettable about these omissions, the amount of detail required to cover them would far exceed both our time and our capacity for absorption of information. There is an additional reason for restricting ourselves to larger (synoptic) scales: namely, the conventional upper air data network does not resolve the smaller scales.

The question of resolution is not a simple one and before proceeding, a few remarks on the nature of meteorological data are in order. Data, in the sense used by experimental sciences (namely, single measurements of an isolated system), are inappropriate to meteorology. Temporal and spatial variability are such inextricable features of meteorological phenomena that isolated measurements at a single location are at best inadequate – and usually useless. Figure 5.1 shows the distribution of radiosonde stations at which conventional meteorological balloon soundings are taken at least once daily (and frequently twice daily at 0000Z and 1200Z). These soundings consist in pressure, temperature, and humidity measurements transmitted by small radio transmitters to the ground. In addition, the balloons are tracked by radar in order to obtain profiles of horizontal wind.