The elements of the picture


IT IS A cliche in popular philosophy that science proceeds by reductionism or analysis, while art, by contrast, is pure synthesis. To put it another way, the scientist likes to break the rainbow into pieces, while the artist puts the rainbow all together again.

Anton Chekov summarised the latter point succinctly: "An artist observes, selects, guesses, and then synthesises.

Ernst Mach, on the other hand, debunked the former thesis at some length: "The reduction of all physical processes to the motions of atoms, must be affirmed to be a chimerical ideal. This ideal has often played an effective part in popular lectures but in the workshop of the serious enquirer it has discharged scarcely any function whatsoever".

Be all this high falutin' theorising as it may, synthesis is essential to the science of meteorology when it comes to building up a picture of our climate. Observations from a myriad different times and places are compiled, compared, and averaged and meaned, until the stage is reached where a detailed statistical description of our Irish weather can emerge. And a good deal more information is necessary for this purpose than can be provided by the 14 hourly observing "synoptic" weather stations around the country. Rainfall, for instance, sometimes varies quite dramatically from place to place, even between locations only a mile or two apart: in order to provide the kind of detail that users of climatological data will find helpful, a much denser network is required.

There are two kinds of supplementary weather stations established for this purpose - simple "rainfall" stations and the rather more elaborate "climatological" stations. There are some 600 rainfall stations in Ireland, where at 9 o'clock each morning the amount of rain which has fallen in the previous 24 hours is carefully measured. From this information detailed - rainfall maps can be constructed, and average and extreme conditions for all parts of the country can be calculated.

Less detail is necessary in the case of temperature and sunshine, because these elements vary less from place to place than is the case with rainfall. Nonetheless, more data is required than the synoptic network can provide, so supplementary information from some 65 climatological stations is used to complete the picture. At these, maximum and minimum temperatures for each 24 hour period are read at 9 o'clock each morning, and a continuous record of sunshine duration is obtained using instruments specially designed for this purpose.