Stormy Weather II

[Old Grumpy]

MrsBBM thinks it will hit 40C, down hereabouts.

Really? I sincerely hope not! Max predicted by Met Office yourabouts is 36°C at 1400. Max myabouts is 39°C at 1400 through to 1600h

[Joseph K]

Despite it being the hottest night on record - it was still 26 degrees here at midnight - I had no trouble sleeping. It's all very different from my younger self when I recall many a sleepless and difficult summer night when in my teens and 20s even though the night time temperature was well below current levels.

How to account for this? Has there been some process of acclimatisation? The heat currently does feel less humid both during the day and night so this might be a factor.

I don't really know but I feel perfectly comfortable in the daytime heat and sleep just as usual at night.

I'm similar. I was thinking though that it may have (almost certainly has done!) helped for me to have given up everything except my medicine - I think caffeine and nicotine ultimately would contribute to drowsiness especially in this weather (to say nothing of other substances).

I notice what I can only call a 'hot' smell which isn't great...

[Dave2002]

One of the main things I remember from the 1975 and '76 heatwaves in Bristol is that sudden strong winds would erupt every day, at around 10-11 pm, as the accumulated heat of the day drained out to the Bristol Channel.

Curious and intereresting. I remember those years as I spent most of my lunch hours playing tennis, then going to the pub, before going back to work later in the afternoon. At the time I worked closed to - but not at - LHR.

Certainly don't recall any strong winds - which I assume happened and were a localised phenomenon.

I didn't experience any particular problems with the heat, though in a later year probably around 1982 I did - and was recommended to increase my salt intake in the morning.

[french frank]

Certainly don't recall any strong winds - which I assume happened and were a localised phenomenon.

Can confirm no strong winds in Bristol yesterday evening, Serial. Today a useful breeze doesn't seem to have made much difference to the 'feel' but we may be now past the heatwave peak (down from 33 to 31 with the coming nightime high at 10pm - 21º). Tomorrow's daytime maximum a mere 24º.

[Petrushka]

Curious and intereresting. I remember those years as I spent most of my lunch hours playing tennis, then going to the pub, before going back to work later in the afternoon. At the time I worked closed to - but not at - LHR.

Certainly don't recall any strong winds - which I assume happened and were a localised phenomenon.

I didn't experience any particular problems with the heat, though in a later year probably around 1982 I did - and was recommended to increase my salt intake in the morning.

Both 1981 and 1982 were reasonably decent summers but the standout summer from that decade was 1984 so might well have been that one.

I was 21/22 in 1975/1976 and it was an unforgettable time to be young, affectionately remembered with great nostalgia.

[Joseph K]

37 now. Possible thunder and rain this evening.

[cloughie]

Thunderstorm this morning - one bolt tripped the electricity and one person in the village lost their internet box leaving black marks around it. The noisy light show and rain didn’t last long and now bright sunshine and 23C.

[Serial_Apologist]

Despite it being the hottest night on record - it was still 26 degrees here at midnight - I had no trouble sleeping. It's all very different from my younger self when I recall many a sleepless and difficult summer night when in my teens and 20s even though the night time temperature was well below current levels.

How to account for this? Has there been some process of acclimatisation? The heat currently does feel less humid both during the day and night so this might be a factor.

I don't really know but I feel perfectly comfortable in the daytime heat and sleep just as usual at night.

One possible reason is this particular heatwave being characterised by low humidity levels, which is quite unusual for this country. In rather simplistic terms it comes down to the esceptional high temperatures of the air originating in France and Spain along with the drying out effect of several weeks' worth in situ.

So, MrsBBM was not far off correct in her assessment of the likelihood of 40C being reached in their neck of the woods - Charlwood (just up the road) having been the first to break the previous record maximum. And that was before midday, which in itself is remarkable - the long-heralded 40C was not reached anywhere officially until 12 noon - at Heathrow - and it would not be surprising if that has not been breached by now somewhere, probably further north as the airstream has had additional warming from overland travel. Here it has maxed out at 35C on my N wall-facing thermometer - which is probably pretty accurate, all nooks and crannies being reached by the heat borne on what is a good moderate breeze. With any luck temperatures will fall from south west to north east as the upper level convergence trough traverses the country later this afternoon - anyone as interested as I in meterological phenomena should take time out to observe this as it happens for what look likely to be interesting cloud formations, as the cloud base is anticipated to be above 12,000 feet, which will offer ideal visibility for cloud-to-cloud lightning, normally only seen at relatively close quarters in textbook surface convection-based storms. More like one sees in Arizona and other misnamed "temperate" desert regions in other words. The danger that such storms often squeeze out precipitation as raindrops evaporate in the hot dry air is that of cloud-to-ground lightning sparking forest and grassland fires.

[DracoM]

Real blustery westerly etting up now.

[oddoneout]

Today has been much worse than yesterday not just because of the overall higher temperatures, but the wind... I don't know what the opposite of windchill is but golly it was here in spades as high teens wasn't enough so went to high 20s mph, peaking at 31. Opening the back door was like opening a bread oven on fan setting and just a very brief trip down the garden was enough to make my skin feel on fire. It's dropped back somewhat as has the temp - only 34 degrees or so round the back of the house, but that's more to do with the sun going round to the front, which is now cooking. The windows, blind and curtains have been closed all day but I think my bedroom may still be too hot to sleep in tonight - it was 29 up there earlier before the full blast of the sun and there won't be any cooling evening breeze, just the current fanheating blast.

[ardcarp]

Railway tracks. There has been much talk (and worry) about railway lines buckling under the intense heat, hence the introduction of speed limits on many routes. Now I've never been a train-spotting nerd, but I do remember learning once, in my youf, that the rails themselves were made in shortish lengths with gaps where they joined (on the fish-plates?). That's why you got the lovely rhythm....diddly dah diddly dah....as the train went along. And the idea was to allow for expansion and contraction with temperature variation. Nowadays, so I understand, rails are continuously welded. OK, it gives a smoother ride, but has the heat expansion thing been forgotten? Maybe an expert could explain, or at least tell me I'm talking rubbish.

[kernelbogey]

To my amazement, spotting with rain here now.

[Joseph K]

Rain! Can see a bit of a rainbow too.

[Andrew Slater]

Railway tracks. There has been much talk (and worry) about railway lines buckling under the intense heat, hence the introduction of speed limits on many routes. Now I've never been a train-spotting nerd, but I do remember learning once, in my youf, that the rails themselves were made in shortish lengths with gaps where they joined (on the fish-plates?). That's why you got the lovely rhythm....diddly dah diddly dah....as the train went along. And the idea was to allow for expansion and contraction with temperature variation. Nowadays, so I understand, rails are continuously welded. OK, it gives a smoother ride, but has the heat expansion thing been forgotten? Maybe an expert could explain, or at least tell me I'm talking rubbish.

I heard an expert today on the World at One (about 12 mins in) explaining that the rails are pre-stressed ('stretched') so that temperature rises simply reduce the stress / tension (up to a point when the rail becomes under compression rather than tension and consequently buckles). (Decreases of temperature increase the stress / tension.) He said that the stress applied relates to the defined working temperature range. A stress temperature of 27 degrees C allows running up to about 38 degrees air temperature. He said that increasing the stress temperature spec. to accommodate higher air temperatures would increase the low temperature withstand, leading to a risk of rails cracking / snapping in winter. Apparently other countries get round it by re-stressing each autumn and spring to change the temperature range - very expensive. (I don't think he said whether there was a limit to the number of stressing cycles.) Apparently HS2 rails will be set in concrete, so will not be able to buckle.

[oddoneout]

I heard an expert today on the World at One (about 12 mins in) explaining that the rails are pre-stressed ('stretched') so that temperature rises simply reduce the stress / tension (up to a point when the rail becomes under compression rather than tension and consequently buckles). (Decreases of temperature increase the stress / tension.) He said that the stress applied relates to the defined working temperature range. A stress temperature of 27 degrees C allows running up to about 38 degrees air temperature. He said that increasing the stress temperature spec. to accommodate higher air temperatures would increase the low temperature withstand, leading to a risk of rails cracking / snapping in winter. Apparently other countries get round it by re-stressing each autumn and spring to change the temperature range - very expensive. (I don't think he said whether there was a limit to the number of stressing cycles.) Apparently HS2 rails will be set in concrete, so will not be able to buckle.

What will they do instead - just ping out?