At midnight in SYNOP reports the total of the previous incoming net solar radiation is reported (or so I think). Many countries report it at this time, others like the French don’t just to be awkward. Here are the values from yesterday across the UK and the near continent (fig 1). I’m not overly clear about the values that I’m displaying or the units I’m using because the WMO manual is suitably vague, and I don’t know what typical daily values to expect at this time of the year. If you know exactly what these totals are please drop me a comment.
The sunniest places in Europe yesterday* were to be found on top of mountains, such as the Sonnblick Observatory on mount Hoher Sonnblick in the Austrian Alps and the Zugspitze Observatory in the Wetterstein Mountains in Germany (fig 1).
* This is only the sunniest of the places that report sunshine in their SYNOP. For some reason most of Scandinavia don’t or won’t, the Netherlands and Belgium do report sunshine, but I think they include it in their midnight observations rather than at the more conventional 06 UTC the next day. I should imagine that the sunshine totals north of the Arctic Circle on a cloudless day in summer are 24.0 hours, speaking of which…
Sunshine in Tromso
Here are the climate statistics for Tromso in northern Norway courtesy of Wikipedia (fig 2) which makes interesting reading (crampons when you’re out shopping on the High street and no frost in June since 1997). Having the advantage of sunshine 24 hours a day in summer I would have thought that the average of 221 hours for the month of June would have been a lot higher. Apparently the sunniest month in Norway was in July 1980 when Tromso recorded 430 hours of sunshine. It’s interesting to see the zero hours of sun for the month of December, there can’t be too many weather stations in the world were the average is in fact a constant like this. I still can’t see why across northern Norway the maximum possible sunshine total for June can’t approach 720 hours (30 x 24)? I suppose it’s back to the question of what constitutes ‘bright’ sunshine I raised in the last blog. All I can imagine is that even when the sky is cloudless, the sun when it’s low on an Arctic summer’s night just isn’t strong enough for maybe four or five hours or so to exceed the threshold set for ‘bright’ sunshine.
UK Sunshine card
These are the hourly sunshine totals for yesterday across the UK (fig 1). As you can see Shoeburyness was marginally the sunniest place with 13.0 hours, but many place across southern areas were close to 100% of the maximum possible. Places like Shoeburyness with the sun rising over the North Sea in the east, and setting over a flat Essex to the west must have a slight advantage over places like Exeter for example, where the sun is slightly blocked by the Blackdown hills to the east and by Dartmoor to the west, which may shave off 0.2 hours on a cloudless day.
Interestingly in my application I made the 13.0 hours at Shoeburyness only 92.2% of the theoretical maximum. Checking on the timeanddate.com website tells me that the day length at Shoeburyness was 14:07:30 for yesterday, so the 13.0 hours of reported sunshine was indeed only 92.0% of the total possible, so the algorithm I use is quite accurate. But what happened to the missing 1:07:30 seconds of sunshine? The total day length would of course start when the top limb of the sun first appeared over the horizon until it disappeared below the horizon in the west, this process may account for 15 minutes or so, but I can’t imagine haze in the atmosphere making up for remaining 0:52:30 on a cloudless day with good visibility like yesterday (fig 2). Who knows perhaps there was some thicker cirrus that went undetected by the LCBR, or maybe we have the threshold for bright sunshine set too high these days, in order to mimic the totals we used to get from the old Campbell-Stokes recorders?
Adding hourly totals works
Reassuringly, as long as you collect all the hourly SYNOP observations, then adding the hourly sunshine totals does produce a figure that’s very close to the one reported at 06 UTC the next day (fig 3).
It shouldn’t be too long before people across the rest of the country see some of the strong spring sunshine we are experiencing at the moment in the more southern parts of the country (fig 1).
The very dull start to April 2018 continues, with many stations across the UK and Ireland reporting less than 20 hours of sunshine for the first 13 days of April, the only bright spots are in the western and northern isles of Scotland, with Stornoway the sunniest place with 67.3 hours (fig 1). There was missing data from both Liscombe and Heathrow.
If you’ve ever read a sunshine card from a Campbell–Stokes sunshine recorder then you’ll probably like this image generated by my SYNOP application. It takes the sunshine reported each hour throughout the day and generates a pseudo mega sunshine trace for all 50 odd SYNOP sunshine reporting stations in the UK (fig 1). I’ve even tried to match the colour of the chart to match that of the sunshine card from memory, but I may not have got the shade quite right.
What today’s mega sunshine card shows is that its been overcast and dull across many parts of the country except the north and west of Scotland and the southwest England, in fact in the Northern Isles the sunshine has been from dawn till dusk by the look of the pseudo trace. The low total from Camborne was a bit of a surprise, but that must have been the convective infill that produced the thunderstorm over west Dartmoor, which produced totals of over 32 mm if my weather radar estimates are to be believed (fig 2).
A thoroughly miserable wet and dull start to April in many parts of the UK, in stark contrast to the unusual warm and sunny spring being enjoyed in parts of Germany and eastern Europe. In the UK the contrast between Cornwall and Devon is large, with Camborne’s 37.8 hours of sunshine over twice that of Exeter’s 18.5 hours and poor old Liscombe with just 7.6 hours. The north and west of Scotland and the extreme west of England and Wales along with southeastern parts have also seen more sun, and the sunniest place in the UK so far this month is Tiree with 47.3 hours, but that figure is low in comparison to the 60 plus hours on the continent (fig 1).
A thoroughly wet start to April across most of the country apart from the drier northeast of Scotland and southeast of England (fig 2). The 19.4 mm from Exeter airport looks dodgy as I’ve already recorded 45.7 mm so far this month only 10 km away to the north. I’m afraid that this spring is looking like it’s going to be a cold wet protracted affair in the UK.
A sunny February (fig 1) ended what was a sunnier than average winter across the UK. I noticed the second sunniest February in the UK as it unfolded, but the second sunniest winter caught me out.
February was the second sunniest since 1929, and the sunniest in the UK since 2008 with 136.8% of the 1981-2010 long-term average. The sunniest regions were generally further west, with parts of Devon, Dorset, Somerset, and south Wales receiving over 170% of the long-term average. February’s are over 10 hours sunnier than they were back in 1929 (fig 2).
Winter sunshine for December, January and February was 122.8% above the long-term average, and was the second sunniest winter since 1929, the furthest that the Met Office can currently be bothered to take the series back to, even if extensive sunshine records exist well back into the Victorian era, thanks to the Campbell–Stokes sunshine recorder, which was invented in 1853. Winters are now over 20 hours sunnier that they were in the age of the Charleston in the UK (fig 3).
The contrast between some of the sunniest areas and the duller spots in western Scotland and Snowdonia is quite striking (fig 4).
Yeovilton in Somerset ended up being the sunniest SYNOP station in February with 129.3 hours of sunshine. Although parts of the south were much sunnier than average, it was a rather dull month for the northeast of England, with Leeming only receiving 68.4 hours of sunshine.
I can’t understand why so many people are complaining about the cold wind of the last few days, it’s given the ground a chance to dry out because of the low humidities, and the sunshine has been a welcome tonic, it’s also given a real fillip to the February totals. A number of SYNOP stations have now received over a 100 hours of sunshine up to the 24th, top of those are Hurn and Yeovilton in WMO bock #03. I notice that Belgium has been even sunnier still, with a total of 138.2 hours at Zeebrugge, that should go a little way to compensate for the dull winter so far.