Weather forecasts: the science behind weather predicting techniques of old - from red skies to pine cones

Weather forecasting - the age-old practice of attempting to predict the whims of Mother Nature. In today's world, we have the latest technology at our fingertips, from Doppler radar to supercomputers crunching complex weather models.

Yet even with all our modern gadgets, forecasters still find themselves scratching their heads at times, baffled by the capriciousness of the weather. After all, with the famously changeable British weather, it often feels like forecasting is more art than science.

One minute, the sun is shining, the next, it's pouring rain. In such mercurial conditions, perhaps it's best to resign ourselves to whatever the weather gods have in store for us today.

But in an era dominated by high-tech satellites and sophisticated algorithms, it's easy to forget the simpler, more whimsical methods of yore, traditions that hold their own quirky charms.

Picture this: a farmer observes his cows suddenly lying down, a shepherd notices the sky blushing crimson at dusk, or perhaps a keen-eyed observer spies pine cones opening or closing.

These are just a few examples of the centuries-old techniques employed in days of yore to forecast the weather. But where did these curious customs originate, and do they hold any scientific merit, or are they merely the stuff of folklore and “old wives' tales”?

Join the thousands of people who already get the NationalWorld newsletter

‘Red sky at night...’

Let's start with the old adage: "Red sky at night, shepherd's delight; red sky in the morning, shepherd's warning."

This age-old rhyme has been passed down through generations, purportedly originating from the sailors of yore. The logic goes that a red sky at sunset indicates clear weather the next day, while a red sky in the morning foretells of approaching rain.

Surprisingly, there's some scientific truth to this rhyme, as a red sky at sunset often indicates that the setting sun's light is passing through a high concentration of dust and moisture particles.

This is typically associated with a high-pressure system moving in from the west, and high-pressure systems generally bring stable and calm weather conditions.

On the other hand, a red sky in the morning suggests that the rising sun is illuminating particles and moisture that have been brought in by an approaching low-pressure system from the east. Low-pressure systems are often associated with unsettled weather, including rain and storms.

Cows lying down?

Then there's the curious case of cows. Legend has it that when cows lie down, rain is nigh, while standing cows signify fair weather ahead. While it may seem far-fetched, there could be a kernel of truth to this bovine barometer.

Cows may indeed seek shelter before a storm, leading them to lie down, though the reliability of this method is dubious at best. After all, cows may simply be lying down out of sheer laziness rather than any innate weather-sensing abilities.

But cows, like many other animals, are sensitive to changes in humidity and temperature, and as a storm approaches, the humidity in the air often increases.

Higher humidity can make it feel cooler and damper, which might prompt cows to lie down, simply as a way of conserving body heat and staying comfortable.

One study by the University of Arizona and North Missouri State University in 2013 attempted to investigate the correlation between cow behaviour and weather patterns, but researchers found no significant evidence that cows lie down more frequently before rain than at other times.

Pine cones

According to folklore, pine cones have the uncanny ability to predict the weather by opening or closing their scales in response to changes in humidity.

Remember that pine cones are the reproductive organs of pine trees, containing seeds that the tree uses to reproduce. When the air is dry, pine cone scales lose moisture and shrink, causing them to stiffen and open up, allowing the seeds inside to disperse more easily.

But when the humidity increases, the scales of the pine cone absorb moisture from the air, causing them to swell and close up. This response helps to protect the seeds inside from getting wet and potentially rotting.

Observing whether pine cones are open or closed can give a quick and basic idea of the current humidity levels, and can provide early clues about imminent weather shifts.

A similar technique using seaweed works in much the same way, and like pine cones, seaweed is hygroscopic, meaning it can absorb moisture from the air. When the weather is dry, seaweed becomes brittle and dry, but when the air is humid or when rain is imminent, it absorbs moisture from the air and becomes damp and flexible.

Can flowers predict the weather?

There are a number of traditional weather forecasting techniques involving flowers, which rely on the sensitivity of certain flowers to changes in humidity, temperature and light, which can indicate impending weather conditions.

For example, common daisies close their petals in response to high humidity and rain, typically opening up again when the weather is dry and sunny, a reaction that is particularly noticeable in the early morning and evening.

The best of the rest

It is sometimes said that if a cat diligently washes behind its ears, rain is on the way. But while cats are meticulous groomers and their behaviour might change with the weather, there's no scientific evidence that their grooming habits are linked to predicting rain.

An old British saying suggests that if soot falls down the chimney, rain will follow. This could be due to changes in air pressure or simply a result of a draft, and while it might coincide with certain weather changes, it’s more likely to be a coincidence than a reliable indicator.

There’s also a belief that spiders spinning larger-than-usual webs indicates upcoming rain, but spider behaviour can be influenced by various factors, including food availability and mating cycles. There’s no scientific basis that links larger webs specifically to weather predictions.