Stormy Weather

[verismissimo]

Miserable day here on the Oxfordshire-Northants border.

[DracoM]

Early snow on tops, very pretty, now sun, but ominous clouds gathering out NW. Wind getting up sneakily. Temp 3C and dropping - at near on noon!!

[Serial_Apologist]

Huge clap of thunder here at, literally, bang on 11 this morning. Nearly spilt my elevenses all down myself! No observable snow in any of the rain down here yet, though the temperature did go down to 3.5 C during that storm. A gust of wind whipped some packaging right out of the air just now as I was attempting to drop it into our recycling bins!

[ferneyhoughgeliebte]

A mixed bag of weather in this part of the Pennines today - overnight rain turned to quite thick snow at around ten this morning. Three hours later, the snow had vanished (except off the hills) and we had clear skies and sunshine - but VERY cold. And now the drizzle has returned.

[Serial_Apologist]

but VERY cold.

My feeling is that the cold feeling, despite the temperature not really being far below what one should expect in this country, at this time of the year, is down to relatively high humidity - which I recently read as being supposed to make air feel warmer. I just don't see this at all. Aren't the coldest-feeling days those with fog in the air? And if it were true, why is it that plunging into water at, say, a temperature of 15 degrees Celsius instantly feels so much colder than standing out in the open air at said temperature in a pair of swimming trunks?

Damp cold air seems to penetrate through clothing protection more than dry air. That said, however, 30 degrees Celsius on a day when humidity is at 90% in Singapore, which is a regular happening, certainly feels a lot hotter than the same temperature in London on hot July day with humidity levels at 30%. I rather expect there to be some cut-off point as one goes down the temperature scale, at which levels of humidity make no difference to chill factor, and below which, the more humid the air, the colder it feels.

[LeMartinPecheur]

My feeling is that the cold feeling, despite the temperature not really being far below what one should expect in this country, at this time of the year, is down to relatively high humidity - which I recently read as being supposed to make air feel warmer. I just don't see this at all. Aren't the coldest-feeling days those with fog in the air? And if it were true, why is it that plunging into water at, say, a temperature of 15 degrees Celsius instantly feels so much colder than standing out in the open air at said temperature in a pair of swimming trunks?

Damp cold air seems to penetrate through clothing protection more than dry air. That said, however, 30 degrees Celsius on a day when humidity is at 90% in Singapore, which is a regular happening, certainly feels a lot hotter than the same temperature in London on hot July day with humidity levels at 30%. I rather expect there to be some cut-off point as one goes down the temperature scale, at which levels of humidity make no difference to chill factor, and below which, the more humid the air, the colder it feels.

IIRC my Physics, this must be to do with some basic physical constants, though I dunno their exact values in this case: heat conduction coefficients and specific heats.

Cold water vs cold air. Water has a vastly higher specific heat than air. This means that you have to put a lot more heat (e.g. from a bunsen burner) to produce a 1 degree rise in the same volume of water as of air. Since in winter weather in each case you are putting your warm body into a colder medium, heat will flow out of you in an attempt to heat the cold medium to equalise the temperatures. A lot more heat in the case of water than air. (Not an experiment to carry out fully at this time of year cos when the temperatures have fully equalised, you'll be dead!)

There is also the matter of the efficiency of the heat-extraction process. Still air is much slower in transferring heat over a set distance than water. It's to do with liquids having vastly more molecules in direct contact with your skin than air does, and the vastly bigger gaps between the gas molecules in air make it more difficult for one hot, fat-moving molecule of gas to transfer energy by collision with one of its colder, slower neighbours. Result: much poorer heat conduction.

We could probably also add in differences in convection rates for a full analysis but I'll stop here

Compared with air, the water vapour in cold damp air adds to what needs heating up because water has a massively high specific heat and latent heat of evaporation (the extra heat you have to put in to get water at 100 degrees C to change itself into vapour at 100 degrees C). Be very grateful for this: it's basically what makes life possible here on Earth!

Water is a completely ridiculous substance - with a molecular weight of 18 one might expect it to be just as gaseous as argon or nitrogen or oxygen That it isn't is all down to hydrogen bonding between adjacent water molecules, which means the chemical formula of water isn't so much H20 as H-10,O-5, a rather bigger molecule with very reduced ambition to be a gas

[Serial_Apologist]

Thank you very much for the detailed explanation, LMP.

I'll read it again...

[DracoM]

Well, whatever, BIG wind oop 'ere as I write, battering at newly repaired slates. Snow forecast.
Fingers crossed.

[EdgeleyRob]

[Serial_Apologist]

The so-called "Fohn" effect only really affects Scotland in any big way in the UK, having mountains high and extensive enough to bring about the leeside drying effect. (Or "Foehn", for pedants insistent of proper umlaut substitutions). It mostly happens in spring to early summer, for a combination of complex reasons.

I thought that, given the dramatic differences between temperatures on the eastern and western sides of Scotland over the past 3 days, I'd re-send this part of a message I posted on this thread back on 20th February. The present weather situation exemplifies what I wrote there, with lovely warm sunny weather affecting the Western Isles to be compared with the cloudy cold conditions being experienced just a few miles across the mountains to the east - the former caused by the warming effect of descending air on the sheltered side of an advancing moist air, which creates the cloud on the side facing the wind, and then, as the air proceeds further on the down slope away from the headwind, it dries out and heats up by compression.

I'm not surprised that we have therefore had no complaints on here from the usual quarters, but I'm afraid your luck is about to run out as you join the rest of us in what has been unseasonally cold for this far into March.

[Serial_Apologist]

I hope everyone's looking forward to the lovely warm sunny Easter weekend we're all about to experience. Is nobody interested in this thread anymore??

Oh, and by the way, don't forget to take your brollies and your wellies.

[ferneyhoughgeliebte]

I hope everyone's looking forward to the lovely warm sunny Easter weekend we're all about to experience. Is nobody interested in this thread anymore??

Oh, and by the way, don't forget to take your brollies and your wellies.

We had some glorious weather this time last week - on the Thursday, I did my first proper walk since October: a four-mile circular walk around Malham (passing Jenet's Foss, Gordale Scar, and back over the tops [possible sightings of peregrine falcons put out of joint by idiot middle-aged man with drone - and I'm not talking about bagpipes! ]). And back to proper work in the garden, too: three hours' wrestling with a fern that emerged in the wrong place - I like ferns (especiallly when they're coiled and waiting to fling) but I have ferns enough (well, I would!) in the garden and needed to be able to see all the stuff behind this vagrant. It didn't half put up a struggle, though!

Since Monday, overcast darker and much cooler.

[DracoM]

It has been SO dry oop 'ere for literally 2-3 weeks that many her are watering gardens etc.
That is NOT to say that the deeper soils are not still pretty saturated, and we are bracing ourselves for a WET w/end here.
Wind has swung round to NW.

[Serial_Apologist]

It has been SO dry oop 'ere for literally 2-3 weeks that many her are watering gardens etc.
That is NOT to say that the deeper soils are not still pretty saturated, and we are bracing ourselves for a WET w/end here.
Wind has swung round to NW.

It was you I was thinking of when I wrote #15310, Draco.

[Serial_Apologist]

We had some glorious weather this time last week - on the Thursday, I did my first proper walk since October: a four-mile circular walk around Malham (passing Jenet's Foss, Gordale Scar, and back over the tops [possible sightings of peregrine falcons put out of joint by idiot middle-aged man with drone - and I'm not talking about bagpipes! ]). And back to proper work in the garden, too: three hours' wrestling with a fern that emerged in the wrong place - I like ferns (especiallly when they're coiled and waiting to fling) but I have ferns enough (well, I would!) in the garden and needed to be able to see all the stuff behind this vagrant. It didn't half put up a struggle, though!

Since Monday, overcast darker and much cooler.

Following doctor's orders, daily walks had become a regular part of my life, and I loved doing them, until a condition known as Plantar fasciitis* hit me a month or so ago unannounced, since when I've been cycling more often in order to alleviate my foot - but that's not so easy to do in long rides as my knee joints aren't what they once were! So I'm quite envious, thinking of your walks in the Peak District.

*https://en.wikipedia.org/wiki/Plantar_fasciitis

A doctor neighbour suggests I acquire some thick soft-soled trainers, and I guess I'll just have to overcome my scruples about said footwear. For the time being it's keeping me working on a biography on a friend who may not be around for much longer, so that provides a good excuse to postpone some kind of solution.

Best of luck with that fern, ferns!