`Authors," said the English essayist Joseph Addison nearly 300 years ago, "have established it as a kind of rule that a man ought to be dull sometimes, since the most severe reader makes allowances for many rests and nodding places in a voluminous writer."
While making no claims to be an author within the normal meaning of the word, your humble scribe will today take advantage of the Addison rule: I shall tell you about anticyclones.
The word "cyclone" was coined in 1842 by the curator of Calcutta Museum, Capt Henry Piddington (17971858); he defined the term in The Sailor's Hornbook, published that year. It derives from the Greek kiklos, meaning "circle" or "coil of a serpent", and is the general name for what we nowadays commonly think of as a depression.
Two decades later, in 1863, a British scientist, Francis Galton (1822-1911), presumably without thinking about it very much, called the opposite phenomenon an "anticyclone".
They are not exciting, anticyclones. These areas of high atmospheric pressure drift aimlessly around the weather map with none of the militant sense of purpose that seems to characterise the behaviour of their antithetical cousins.
Indeed they exist, one might almost say, as mere foils to the volatile itinerant depressions. Unlike a depression, which has a clearly defined centre of low pressure, it is usually difficult to find the corresponding "peak" of an anticyclone.
Indeed it is more like a plateau, with the barometric pressure changing by only a small amount over a large central area, producing very light winds of variable direction.
Anticyclones result in different weather scenarios, depending on the time of year. The predominantly clear skies that normally accompany them have given rise to Ireland's warmest summer weather and also to the severest winter frosts we have ever known.
In autumn and winter the very calm, clear conditions of an anticyclone, combined with the long nights, allow the ground to lose a great deal of heat; this results in very low air temperatures, and often fog. The feeble winter sunshine finds it difficult to disperse this fog, so mist or low cloud may persist, on and off, for several days.
But in spring and summer solar heating is strong, and the temperature rises quickly after sunrise. At this time of year clear sunny skies over several days and the resulting accumulation of solar heat bring about a gradual but steady rise in temperature - and may even bring a mini-heatwave. Enjoy it while you have it, if you can.