One small warning please: Due to the hugely variable nature of weather, this post is only really relevant to the UK. Sorry.
It was my birthday yesterday and while I was walking to my mother’s house, I wore a winter coat while getting rained on. This has never, ever, happened before in my life. My birthday is always a scorching day, the Sun’s always been an enthusiastic guest at childhood parties and my clothing issue is generally ‘euuurgh I hate not wearing tights’ not ‘why have I packed away my raincoat and scarf?’ … I mean it’s in the 16th of July after all.
Obviously we’re used to rainy Summers, here in England. But it’s generally a bit or some or even a lot of rain, not just all rain – full stop. This year we’ve had the wettest April to June on record, and recently we had more rain in a day than we usually get in all of July. Floods have been happening left right and centre and I’ve even seen tongue-in-cheek ”missing – reward for handing in” posters for our old friend who never seems to visit any more, the Sun.
So what’s the reason for all this nonsense?
I was curious (and a little irritated) so I bore my questions to the modern-day Oracle- Google. Luckily Google’s annoying answers remain in the realm of ”are you sure you didn’t mean blah blah blah” and don’t stray into ”the answer is inside yourself” territory. That would just be too much. Anyway, what I discovered was that our lack-of-Summer is due to the Polar jet stream basically dancing about and not being where it’s meant to be. If you don’t know, a jet stream is a long and narrow intense wind current that flows through the atmosphere, roughly where the troposphere and the stratosphere meet. The Earth has four, one polar and one subtropical jet stream in each hemisphere. It’s kind of like the air is walking or cycling around most of the atmosphere, but the jet streams are the motorways. They can move up to 200 miles per hour, moving from west to east across the globe.
The jet streams play a large part in guiding patterns of rainfall. The northern polar jet stream that determines much of the UK’s weather is not where it usually is this year. Usually it’s north of the UK in Summer, pushing the wet weather further north and allowing Britain to have relatively dry and sunny conditions… But this Summer it’s been further South, driving all the rain right into the UK. This is where it tends to be in the Winter. Now it’s important to understand that this isn’t exactly alien, the jet streams move around all the time and our one frequently moves into this southerly Wintertime position in the Summer months… It’s just that it’s very unusual for it to stay in that area for so long at this time of year.
I couldn’t find a solid answer as to why this has happened. Climate science is so complex that it’s basically impossible to infer true cause and effect… I mean you can’t design an experiment with something that’s out of your control, so you have to use natural studies, and they’re not as clear cut. Anyway according to the MET office, climate scientists think climate change is causing these unusual jet stream patterns and it could be something to do with the record-low level of sea ice in the Arctic. Also the warmer air is the more moisture it can hold, so the general trend of rising atmospheric temperature means that these days, when rain occurs, there’s simply more of it to fall. Since pre-industrial times, average atmospheric temperature has gone up 0.7% and moisture content has gone up by 4-5% to match. *
So there we go. The Sun hasn’t abandoned us, it’s just this pesky jet stream is being weird. By the way, the same positioning that is making Britain into a quagmire is throwing America into severe drought. But here’s some good news: Weather reports say the polar jet stream is set to rise northward soon, possibly giving us just a week or so more rain before allowing an actual Summer to peek it’s head out from behind the fast-exiting clouds.
Well hallelujah, because I want to wear my new sandals at least a second time before having to don Winter boots!
http://www.bbc.co.uk/news/science-environment-18868494 – picture credits for second and third image.
First image from Google Images.