Maybe not for the art historian, but certainly for the meteorologist, one of J.M.W. Turner's most captivating works is Buttermere Lake, with Part of Cromackwater - a Shower. It was painted in the late 1790s, when Turner was a mere stripling of a lad of 22, and had yet to adopt his unconventional and somewhat controversial later style.
Buttermere Lake is a faithful reproduction of a lakeland scene on a dark and sombre rainy day. However, there is a break in the sky behind the artist to allow the sunlight through, since the picture is dominated by a perfect rainbow, the spectral colours being portrayed correctly with the red outside. But the painting, in fact, shows three rainbows: clearly visible outside the primary bow is the not uncommon secondary rainbow, and there is also a reflected rainbow - what appears to be a portion of the primary arc reflected from the surface of the lake below.
Turner at the time was painting in our own climatic region where dramatic rainbows are not all that uncommon. The cool showery conditions that occur frequently in Ireland, Wales and Scotland, where broken skies allow sunshine to stream through to hit a distant curtain of very large raindrops, are ideal for the formation of a rainbow, and they can sometimes last for some considerable time. Indeed it was on this day 19 years ago that there occurred in these parts what, so far, has proved to be the rainbow of the longest duration ever seen.
It was the day of the tragic Fastnet yacht race on August 14th, 1979. The storm that caused the disaster had appeared as a minor disturbance near Nova Scotia on the weather chart a few days previously. As it moved across the Atlantic, it intensified explosively and unexpectedly; winds of hurricane force reached the Fastnet area just before 11 p.m. on August 13th, and during the next six hours waves some 40 to 50 feet in height resulted in the loss of 18 lives.
But the clouds of the Fastnet storm had, if not a silver, then a multicoloured lining. The depression responsible for the havoc moved across Ireland early on August 14th, and by evening it had reached the east coast of Scotland. During the afternoon it provided a showery north-westerly flow of air over north Wales, and it was there, near Llandudno, that these showers, merging one into the other and yet allowing access to the sunlight, produced a rainbow that lasted for a full three hours without a break.