The Brits are obsessed with the weather, for the simple fact that it is so changeable in the British Isles. But what did they do before the advent meteorology, supercomputers and the “Shipping Forecast”?
In an economy that was built on maritime trade and agriculture, it was important for sailors and farmers to be able to predict the weather as accurately as possible. One way in which people attempted to do this was by observing nature, often by studying cloud formations, the moon or the behavior of animals and plants. Sometimes they looked at the weather on a landmark day – such as St Swithun’s Day (15 July) – and simply used this to predict what would happen over the coming days, or they would chant simple incantations in a bid to magic away adverse weather.
As with much folklore, this was learnt at an early age, frequently as nursery rhymes – for instance, “Rain, rain go away; come again another day” and it’s variations – which many of us remember from own childhood. In fact, weather lore has been important all around the world and similar rhymes can be found from many societies, including ancient Greece.
In the case of St Swithun’s Day, tradition has it that, if it rained on that day, it would continue to rain for 40 days consecutively: “St Swithun’s day if thou dost rain, for 40 days it will remain. St Swithun’s day if thou be fair, for 40 days ‘twill rain nae mare.” The location of the Jet Stream actually does play an important role in determining northern European weather shortly after the summer solstice: if the jet stream is in a southerly position, then areas to the north are likely to experience a more unsettled summer; alternatively, If the jet stream is in a northerly position, then the weather is likely to be brighter and dry throughout summer. That said, there have been no instances of rain for 40 days and 40 nights since records began, according to Britain’s Met Office.
Red Sky at Night
Perhaps the most famous piece of weather advice is: “Red sky at night, shepherd's delight. Red sky in the morning, shepherd's warning.” This dates back at least as far as biblical times and appears in the Gospel of St Matthew. Global variations include “Red sky at night, sailors delight. Red sky in morning, sailors warning”.
So, is there any truth in it? According to the Met Office, the saying is most reliable when weather systems predominantly come from the west, as they do in the UK. A red sky happens when dust and small particles are trapped in the atmosphere by high pressure; these conditions scatter blue light, leaving only red light to tinge the sky. A red sunset generally means high pressure is moving in from the west so therefore the next day will usually be dry and pleasant.
Thus, where westerly weather systems are common, “Red sky at night, shepherds delight” often turns out to be true, since it tends to indicate that fair weather is generally headed towards us. Conversely, “Red sky in the morning, shepherds warning” means a red sky appears because the high-pressure weather system has already moved east, indicating the fine weather has passed, most likely making way for a wet and windy low-pressure system.
In the United States and Canada, Groundhog Day is celebrated on Candlemas Day, 2 February. According to the folklore, if it is cloudy when a groundhog emerges from its burrow on this day, then spring will come early; if it is sunny, the groundhog will supposedly see its shadow and retreat back into its burrow, and the winter weather will persist for six more weeks. The largest Groundhog Day celebration is held in Punxsutawney, Pennsylvania, where crowds as large as 40,000 have gathered to celebrate the holiday since at least 1886.
The festival has its origins in ancient European weather lore, in which a badger or sacred bear is the prognosticator (the maker of the prediction), as opposed to a groundhog, woodchuck or marmot. It bears similarities to the pagan festival of Imbolc (the seasonal turning point of the Celtic calendar, which is also celebrated on February 2 and involves weather prognostication), and to the aforementioned St Swithun’s Day.
Like much weather folklore, the Groundhog Day custom is founded on observation of the natural world, in this case the reappearance of hibernating animals or those that stay below ground to avoid the excesses of winter; thus, badgers, hedgehogs and bears were a sign of winter's end. When German settlers came to Pennsylvania in the 1700s, they chose the groundhog as the local harbinger of spring.
The custom melds the harbinger of spring (an animal emerging from hibernation) with a sign of winter – clear, cold days – and combines them with a date that has astronomical significance: the date exactly halfway between the winter solstice and the spring equinox.
Haloes and Coronae
“When halo rings Moon or Sun, rain’s approaching on the run” is another piece of folklore with an element of truth. When a ring appears around the Moon or Sun, this can be caused by ice crystals that have formed in high clouds and is often referred to as a halo or icebow; these crystals refract the light from the Moon or Sun. When the ice travels lower, precipitation becomes more likely. In summer months particularly, a halo can be a sign of approaching storms. A corona is a slightly different phenomenon: a series of concentric rings caused by the light of the Sun or Moon diffracting around water droplets.
“Mackerel sky and mare’s tails make tall ships carry low sails” – this nautical proverb originates from the days of sailing ships. A “mackerel sky” is associated with altocumulus clouds – the clouds are said to resemble the scales of the mackerel (a fish) – while “mare’s tails” refer to cirrus clouds. Both could develop before an oncoming storm during which the crew would need to lower a ship’s sails. Altocumulus clouds appear when there is a certain level of moisture in the air suggesting rainfall is approaching.
Are Animals Natural Weather Forecasters?
There are many instances of animals and plants being sensitive to oncoming weather events and other natural phenomena, including elephants reportedly fleeing to higher ground in advance of an imminent tsunami. Crickets, for instance, can be accurate temperature gauges, chirping faster when warm and slower when cold.
Migration patterns also mark the passage of the seasons. Even today, we watch for animals to indicate the change of seasons. Geese flying south is a sure sign of fall in the United States. In the Midwest and Northeast, people wait for the first robin of spring, while Californians wait for the swallows to return to Capistrano. Meanwhile, Ohio residents know it's spring when the buzzards come back to Hinkley.
While many sayings are probably fanciful such as “the hooting of the owl brings rain”, there is some truth behind others. One example is: “When the milkweed closes its pod, expect rain.” Because the plant needs to avoid its seeds becoming waterlogged so that they will float on the wind to aid dispersal, it closes up its seedpods in advance of oncoming rain. This is just one of many examples of living organisms responding to impending weather changes – a potentially fruitful area of research.
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