The world is familiar now with El Nino and its eccentricities, and is happy to blame it for anything meteorologically unusual from Timbuktu to Timahoe. But the inhabitants of the Peruvian coast of South America experience from time to time a visible reminder of its influence.
It is responsible for the periodic occurrence of the "Callao painter", an effect similar to that noted by Hamlet when he remarked:
This most excellent canopy the air,
This brave o'erhanging firmament, this majestical roof
Fretted with golden fire,
Why, it appears no other thing to me
But a foul and pestilential congregation of vapours.
The origins of El Nino, a term which we now apply to a periodic warming of the surface waters of large areas of the tropical Pacific, can be traced to the centuries-old observation that near the end of each calendar year a weak ocean current starts to flow slowly southwards along the west coast of South America.
Long ago, the inhabitants of these coastal regions gave this warm current a name; they called it Corriente del Nino, the Christ Child Current, because it came nearly every year at Christmas time. It was also noticed, moreover, that every few years the Corriente del Nino was particularly intense - coinciding with the phenomenon that we now know as El Nino.
Now, along the west coast of Peru the warm waters of an El Nino bring refreshing rains, and the desert springs to life with many kinds of exotic plants and flowers.
But the visitor brings other, much less welcome, gifts as well. The warm influx is lacking in the nutrients normally present in the colder water, and this has a dramatic effect upon aquatic life.
First, many tiny planktonic organisms die, and then the larger ones that feed on them - and so on up the ecological scale to fish, and to the birds that feed upon the fish.
As marine life succumbs to this periodic famine, dead fish and birds litter the beaches and the coastal waters of Peru. The process of decay turns the sea a ruddy shade of brown, and hydrogen sulphide, a pungent by-product of decomposition, is released into the atmosphere.
But this unpleasant phenomenon, sometimes known as the aguaje, has another quality in addition to its sickly smell: the gas attacks and blackens the paint-work of any ships in the vicinity.
This latter side-effect is particularly noticeable at Callao, the port of Lima and the most important in Peru, and hence the phenomenon has come to be known widely throughout the region by the name "Callao painter".