April 22, 2024


Do you remember as a child jumping in puddles dressed in short red wellington boots and holding a brightly coloured little umbrella? Sometimes rain can seem quite fun whether it is great fat droplets that splash down or a moody almost opaque mizzle, torrential rain to run out into and then back into the dry or rain that you just watch through a window pane. I suspect however that most people in this country would currently say that they had had quite enough of it as it seems to have rained almost incessantly now for several months. We have just enjoyed a few days of sunshine which was heavenly and, today, guess what, it is raining.

“Rain” is an Anglo Saxon/Germanic/ Dutch word stemming from those colder northern European climates. The romance languages with their Latin associations use pluvia – il pleut or la lluvia for example in Spanish which suggests showers rather than the incessant grey rain around the Atlantic and Baltic seas.

The British do like to talk about the weather. With a predilection for outside concerts, picnics, walks, runs and events, it is always one of the biggest risk factors. We tend therefore to be glued to the weather forecasts, in a myriad of media, trying different versions until we find the result we most prefer.

Most of the British weather patterns can be predicted from the rivers of air circulating high above us. The jet stream is a core of strong winds above the Atlantic Ocean which moves and meanders rather like a current in a river, splitting up and swirling together but for us always in a west to east direction. Like a river, the effects are strongest in the centre and more eddying towards the edges. It is the consequence of the differences in heat and thus pressure between the equator and the poles. In winter when the temperature difference is more marked, the unevenness causes greater edginess – or turbulence – in the jet stream and thus wetter, stormier weather.

In summertime there tends to be a smaller temperature difference and the position of the jet stream hopefully ends up to the north of the UK so that we see calmer, drier weather. The jet streams also “follow the sun” – as the sun’s elevation increases each day in the spring, so the average latitude of the jet stream should shift polewards.

The sun rises in the east and sets in the west but because the earth rotates, our view of this is relative. The jet streams also eddy and move in relation to the rotation of the earth. Since the Earth makes one rotation every 24 hours, the countries along the longer latitudes towards the equator rotate at a faster speed than Britain does for example because they travel further in the same amount of time. Therefore, the Earth’s rotational speed is fastest at its widest point, the equator. Likewise, if you stood at either the north or south pole you would not really move, just slowly turn around. The result of this is that the air moving away from the equator does not move directly north and south because it retains this rotational momentum.

However, in reality there are no simple answers to the weather patterns because, like so much on this earth, there are a myriad of subtle connections and inter-relationships and a multiplicity of subtle influences which all play their part.

In the past we were more conscious of the natural landscape in which we lived and knew the seasonal patterns and clues as to the weather. We looked at the clouds, sniffed the air and watched the animals. There were a multitude of country sayings which acted as guides which perhaps surprisingly are still often valid today, for example, the saying “doors and drawers stick before a rain”. In a nutshell, wood expands when the air humidifies, humidity is a sign of low air pressure and incoming bad weather so yes – a door suddenly sticking can indeed sometimes predict rain.

Ultimately though there is nothing so satisfying as lying on your back and watching the clouds. To quote one of my favourites A A Milne:

“How sweet to be a cloud. Floating in the Blue!”