"THE winds and waves", according to Edward Gibbons in The Decline and Fall of the Roman Empire, "are always on the side of the ablest navigators." Years of experience battling the elements give them an insight that no amount of bookish learning can provide.
Thus, when mariners stoutly maintained for generations that sometimes with the onset of a bout of heavy rain the seas grow calm, meteorologists, of course, believed it but they could find no evidence of such a phenomenon themselves nor discover any reason why it should be so.
But just recently however, satellite images have proved the sailors were correct. Some environmental spacecraft nowadays carry radar equipment which bounces microwaves from the earth's surface and reassembles the reflected beams into an image.
Since the microwaves can penetrate cloud, pictures can be obtained in conditions when visual images would be impossible.
A side effect of this type of observation and sometimes a very useful one indeed is that rough seas reflect the radar beams in a different way from calm ones.
In this way, scientists have discovered that, from time to time, there occur upon the oceans anomalous areas of relative calm, each five or 10 miles across and dotted over an area of ocean experiencing heavy showers at the time.
Moreover, when these calm footprints", as they are called, are compared with the images of thundery showers from earth based weather radar, it has been found that the two exactly coincide there is an area of relative calm directly beneath each thundercould.
The explanation is believed to lie in the flow of air within a shower cloud. Heavy showers have their origins in atmospheric updraughts, but the rising fountains of air have their counterparts in equally strong down draughts downward surges of air which hit the surface of the sea and burst out horizontally around the point of impact, rather like the stream of water from a tap when it strikes the bottom of the kitchen sink.
A possible interpretation of the satellite anomalies is that the blast of descending air dampens the existing waves in an area immediately beneath the shower clouds, albeit causing even larger waves elsewhere in the vicinity.
And since the core of the down draught usually coincides with the zone of maximum heavy rainfall, it is easy to see why the rain might seem, as the mariners had said, to have a calming effect upon the sea.
Byron said: Of all the horrid, hideous notes of woe
Sadder than the owl songs or the midnight blast
Is that portentous phrase, "I told you so."