One small warning please: Due to the hugely variable nature of weather, this post is only really relevant to the UK. Sorry.
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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!
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References:
* http://metofficenews.wordpress.com/2012/07/12/the-uks-wet-summer-the-jet-stream-and-climate-change/
http://www.bbc.co.uk/news/science-environment-18868494 – picture credits for second and third image.
http://en.wikipedia.org/wiki/Jet_stream
First image from Google Images.
Earth Baby 
This is an EXCELLENT post! I’ve heard some people say that “global weirding” might be a more appropriate term than “global warming” because so much of what we’re seeing is odd disruptions in normal weather patterns. Here in Colorado we’re suffering through a terrible drought, and the hottest summer on record. I’m sitting here trying to decide if it’s worth it to go for a bike ride since it’s 92F out there (33C.) Sounds sorta miserable to me, but this is the coolest day we’re likely to get for the foreseeable future – so maybe I should brave the heat and go for it. I’ve gotta say though… if this is the “new normal” I’m not really looking forward to what the future has in store!
Hey, thanks so much, glad you like it! I agree with ‘global weirding’, ‘climate chaos’ etc being good terms to use. It sounds pretty hot down your way… I read a news article saying that the US was experiencing heatwaves and droughts- as you can see from my post here in the UK we have the exact opposite. Hello extreme weather and weird climate disruptions! I guess we can expect this to continue….
I wish I could share some of the heat we have been having. I love summer, but 90-100 degrees day after day for couple of months has been getting to me. Normally we rarely see a temp in the 90s. Around here we live by old farmer’s signs and the farmer’s almanac. One sign we look for is a type of caterpillar we call a wooly bear. It’s “coat” is a mix of black and brown bands. The size of the bands is supposed to be telling of what the next winter is supposed to bring. So far we have found all black caterpillars, which in this scenario would mean one long and really bad winter to come. People around here are shaking their heads, having never seen one like this before. I think we all need to get used to not knowing what will come as the “unusual” seasons may become our norm.
Wow, thanks for sharing this about how you use nature’s signs to show what is to come… I love hearing about this sort of stuff but where I live all that is lost.. It’s more ‘new-age’ than anything. May I ask where you live?
I live in Pennsylvania, there were plenty of large family farms and people generally learned to watch the signs of nature to help them decide when to plant, when to harvest. Thankfully, there are plenty of people still around willing to share their knowledge with those of us who didn’t grow up on the farms.