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BBC are quoting this in their article about the heavy rain in Spain.
People have also been advised to avoid unnecessary trips in the north-eastern city of Alcanar, Tarragona - where 215 litres per square meter of rain has fallen in the past 24 hours.
https://www.bbc.co.uk/news/world-europe-66702891
Initially it seems like it must be a typo/mistake and I read it several times before I googled the quote and found several outlets with the same text, and another stating
120 litres per square metre of rain could fall over 12 hours in Madrid
So is this just a weird method of measurement that makes it appear more significant? (And clumsily written, as 215 litres of rain per square metre would seem to be a simpler way of saying it)
I think 215 litres of rain per square metre would be the same as simply stating 215mm of rainfall?
I think you are right - we'd say 21.5cm of rain.
To my head, that makes it easier to contextualise. That’s (pretty much) a quarter of a ton of rain, per square meter. That’s pretty wet!
I prefer 2.7 million pints per football field.
I'd prefer it was measured in metres as I'm unclear why we'd be using gas meters as a form of measurement...
I think you are right – we’d say
21.5cm of rainblinkin wet.
😆
I think it would be easier to visualize if they said an average elephant weight of rain spread over the area of a large SUV.
215mm of rainfall, thats alot, ardrock on the sunday got about 18mm overnight, and that was saturated.
Litres per meter would be a normal way to state a unit of measure, so I'm happy with that.
I also think that using different methods to describe a 'thing' is a good way to make people think about the concept. mm are tiny, so 215 of them still isn't much and without the context of a square meter that could be spread over miles and miles if you're not familiar with how rain measure works.
215 medium bottles of coke balanced on my desk though... 😨
Means nothing unless it’s in units of a proportion of the size of Wales.
Typical weather we'd say in Manchester
Means nothing unless it’s in units of a proportion of the size of Whales.
FTFY!
I'll ask my youngest, he was in Valencia last night, said he'd never seen rain like it.
2.5 trillion pints per wales. (2.5e12 if you want to argue the merits of billions vs trillions...)
Yes, that unit of measurement took a bit of getting used to when we moved here 8 years ago. We had some flash flooding around here over the weekend, the problem is run off from ground which is baked hard from months of no rain. When we used to quote inches of rain in the UK I guess people get used to the concept that 4 inches of rain in a day is quite a lot without really understanding the test method.
Another difference in continental Europe is measuring vehicle fuel consumption in litres per 100km which means the lower the number, the more economical the vehicle rather than the higher the mpg the better.
I think you are right – we’d say [s]21.5cm of rain[/s] [s]blinkin[/s] [b]average day in Argyll[/b] wet.
Thing about measuring rainfall is that the area it's falling on makes no difference to the first figure, so 215mm of rain is 215mm of rain per square metre, or 215mm per Offa's Dyke squared, (6,724 square miles or 430,336 square furlongs) Or in old money it's 8.46 inches of rain.
So, Wales is 20,782 square kilometres so that 20,782,000,000 square metres. So in terms of litres of water, that's 4,468,130,000,000 litres of water per Wales.
I guess people get used to the concept that 4 inches of rain in a day is quite a lot without really understanding the test method.
There's a lot less to understand though - 4inches is 4 inches, tin, bucket, paddling pool, any area with straight sides and no runoff, they'll be 4 inches of water deeper by the end of the day.
Litres per meter means you have to translate it into water depth to picture it, or just contextualise with past experience of measures - which, to be honest, is what we have to do with more "normal" measures of rain anyway- 1 mm of rain in a three hour slot - is that light rain? medium rain? wet air?
Typical weather we’d say in Manchester
Lol no. Brits like to moan about rain, but in terms of volume we get bugger all. There are some proper wet places out there. UK does NOT get a lot of actual rain, the problem is that it can be cold rainy and wet at any time of year, including all winter long or during your summer holidays.
Another difference in continental Europe is measuring vehicle fuel consumption in litres per 100km
Big fan of this, or litres per 100 miles if we can't multiply by 1.6. Even better then to convert the fuel into £ (which i know varies as fuel price varies but in the end is what we really care about - burn me environmentalists!)
I get 42mpg in my car on a run to Leamington to my daughter's Uni - so when i had to drive there and back this weekend to pick up the keys to her house - that's 42 miles per 4.5 litres of fuel approx. 42 miles per £6.90, £16.50 per 100 miles approx.
240 mile round trip, £40. Plus I had to buy my wife brunch (Boston tea party, recommended) and a cardigan in the White Stuff sale, means it cost me over £100 to pick up her keys. because she was at work, and earned about £90. Man maths makes me think she's nearly £200 up on this deal, and therefore to balance out I'm £200 down..... I wish i hadn't worked that out now!!
I'm a great fan of acre-feet as a measure of volume. Used to measure dams in the USA e.g. the Hoover dam contains 28,945,000 acre-feet. Makes sense when you're thinking about flooding and irrigation.
I'm having trouble visualising the litres per Wales thing, can someone translate it to swimming pools (olympic) please. Also, if someone would like to calculate the volume of double decker bus and see how many of those it would be per Wales it would be appreciated.
Nonsense, double decker busses are only used for the measure of motorcycle jumps.
There’s a lot less to understand though – 4inches is 4 inches, tin, bucket, paddling pool, any area with straight sides and no runoff, they’ll be 4 inches of water deeper by the end of the day.
It's all fairly academic though, 215 l/m2 is 215mm, if you can get used to visualizing that in inches then you can get your head around a unit that needs no conversion at all.
Understanding inches of rainfall requires the understanding of:
1) The imperial system; 4 inches,
whats that,
ohh 16 grains,
of corn?
No Wheat I think?
With or without the husk?
No idea?
What about bulgar wheat?
Ohh FFS it's just slightly less than 10cm OK!
How much less?
About a 1/16 of an inch
1/4 of a wheat grain then?
No, thats a few thous out
Thous of a wheat grain?
No Thous of an inch
You mean 250th's of a wheat grain then?
No, don't be daft that would be a silly measurement.
2) An understanding of dimensionality reduction. The concept that you can describe something that's clearly a volume (has anyone ever said "that's a large height of rain", no, it's clearly "that's a high volume of rainfall" in less than three dimensions.
[I'm now re reading that as an argument between Blackadder and Baldrick, imagine a 5th series where they're a union working at British Leyland using imperial bolts of the mechanics and metric ones for the electrical systems, because ...... reasons]
I think you are right – we’d say 21.5cm of rain
We ****ing wouldn't.
We use mm and m as our units.
Yours sincerely Joshvegas a user of actual rainfall data to design flood defences.
I can see why this makes sense. I can remember a Georgraphy teacher telling me her students couldn’t see the implications of 200mm of rain in terms of the volume of water that would need to enter rivers etc.
I’ll confess this came up in a physics lesson recently. If you pour 1 litre of water into a tank, 1m on each side, that’s just 1mm at the bottom of the tank. The maths is clear but we were still a bit surprised
A standard GM double decker varies in length, so the figures may be a bit too vague for some. However, if we measure the bus in chains it might be easier.
We'll go for 0.5 chains in length, (mean)
They are 0.124 chains wide
They are 0.218723 chains high
So the bus has a volume of 0.01356083 cubic chains.
To convert cubic chains to litres you simply multiply by 8.14 x 10e+6
Wales has therefore been covered by 548844.23372250318 cubic chains of water,
or, more accurately, 40,472,761.16008409367273242124 double decker buses.
I can see why this makes sense. I can remember a Georgraphy teacher telling me her students couldn’t see the implications of 200mm of rain in terms of the volume of water that would need to enter rivers etc.
Agreed. I have used bottles of coke to illustrate how much flow 2litres a second is.
Ie "imagine I through a bottle of coke for you to catch every second"
To my head, that makes it easier to contextualise. That’s (pretty much) a quarter of a ton of rain, per square meter.
do you find that easier? I guess we are all wired differently, but thats vastly overcomplicating it. And it requires the knowledge that 1L water = 1kg, and a vague ability to visualise weight. Both of which are lacking from the general population.
215mm of rain, or 8 inches of rain means just that. Everywhere would be covered 8 inches deep (were it not for drainage) or if it fell instantaneously. For me thats quite easy to visualise.
What Scapegoat said. Added words... no added meaning or aid to understanding.
TINAS and Scapegoat win this thread. 🤣
Measuring rainfall in bus-chains per Wales, that's awesome. I'd love to hear that slipped into a BBC weather forecast.
Thank my physics teacher Mr Wilkinson. We once did a lesson on expressing velocity in furlongs per fortnight.
Thank you Mr Wilkinson, and to everyone else who’s calculated rainfall in the new standard unit of double decker buses per Wales.
@joshvegas, I’ll expect you to disseminate this new, more intuitive, unit amongst your flood defence colleagues.
A standard GM double decker varies in length, so the figures may be a bit too vague for some. However, if we measure the bus in chains it might be easier.
We’ll go for 0.5 chains in length, (mean)
They are 0.124 chains wide
They are 0.218723 chains high
So the bus has a volume of 0.01356083 cubic chains.
To convert cubic chains to litres you simply multiply by 8.14 x 10e+6
Wales has therefore been covered by 548844.23372250318 cubic chains of water,
or, more accurately, 40,472,761.16008409367273242124 double decker buses.
What units of time are we using? O:-)
Dunno about the units, but can confirm it's been a very wet couple of days here in Madrid.
Litres is a bit complex.
Hopefully it'll soon be simplified to X Olympics swimming pools per football pitch.
TINAS and Scapegoat win this thread. 🤣
Trouble is, I've spent he rest of the morning trying to figure out if there's a dimensionless measure for rainfall.
I think it should be possible because after a long enough drop the raindrops are in equilibrium, as I would make the hypothesis that for every drops that collide and form a larger one (which then accelerates) another is pulled apart by frictional forces. However the heavier the rain, the more collisions you have and the further towards larger drops the equilibrium moves. Thus I believe it should be possible to express the intensity of rainfall in terms of the mean and standard distributions of it's Reynolds number?
Needs a banana for scale
Too many variables but I'll have a go:
A modern banana shipping box holds about 18kg of bananas, they measure 53.5 × 40 × 24.5 cm so and have a volume of approximately 52 litres- 52.42litres to be exact. A double decker bus has a volume of 110m3, or 110,000 litres, so would hold 2115 boxes and leave room for a tiny Welsh conductor.
1 kg of bananas is between 7 and 9 fruit according to grocery websites, so we'll stick with 8 per kg. 18x8=144(bananas per 18kg box) multiplied by 2115 (boxes per double decker )=304,560 bananas per bus.
So, you'll be able to get a mental image of 12,326,384,138,915.2115689673862128544 bananas and a shitload of little Welsh conductors.
@Scapegoat - has the banana stacking conjecture finally been solved then?
What units of time are we using? O:-)
One sixteenth of an Eisteddfod, or overnight if you're fussy.....
That's a lot of potassium
Rain is liquid....and when it falls from the sky the pesky ground absorbs it (until it doesn't) and if not absorbed pesky gravity makes it run away somewhere else (unless you are at the low point in which case it all runs to you) so it doesn't make sense to measure it in a nice impossibly even non absorbent sheet collecting on the floor. Measuring it in litres....like I would for other liquids (not gallons, quarts and fluid ounces - I'm not a bloody heathen) makes lots of sense to me.
Unless of course you measure in Wales, whales, buses (double decker obvs) or Olympic swimming pools.....
However I'm 51 and if I'm honest I reckon my prostate is not too healthy so identify with something else - I'd measure it in middle aged man's night time toilet trips. Now, it's been a while since I pissed in the kitchen measuring jug (for science) but I reckon I'm a good 400ml a trip man. So that's 537.5 walks of shame - or about a months worth if rounding up. I'm not sure what a 0.5 of a trip is..........getting half way and pissing in your partner's slippers? As it happens my shower cubicle is almost exactly 1m2 - QED the rain in Spain, didn't fall on the plane, but it was me having 537.5 night time slashes in the shower (you all do that right?).
I want all these units recalculated in Smoots.
https://www.atlasobscura.com/places/harvard-bridge-smoot-measurements
Anyway-
215mm of rain in 24hr is a lot.
In July this year - the wettest month of the year so far - I recorded a mere 165 mm in my back garden.
One sixteenth of an Eisteddfod, or overnight if you’re fussy…..
Does that mean that we can simply multiply by 16 and have a unit of buses per Wales-Eisteddfod?
That’s a lot of potassium
4,412,845,521,731,645.7416903242642018752 mg based on 358mg per 'nana
At an RDA of 3500 mg, that enough potassium to lower the blood pressure of 840,542,004.13936109365529985984 male voice choirs for a month now that their conductors are stuck on the bus.
But Bananas have ionizing radiation
https://en.wikipedia.org/wiki/Banana_equivalent_dose
So 12,326,384,138,915.2115689673862128544 banana's means there's 352182.403969006 acute lethal doses.
Excluding deaths caused directly by crushing, or the indigestion caused by trying to eat 35million bananas, or aneurisms caused by the logistical headache of trying to move that many bananas to Wales.
In that case the Male Voice Choirs can have a couple of months off seeing as the conductor has involuntarily hung up his baton.