Scotland/Alba weather discussion - Jan 2021 onwards

[Hairy Celt]

Just now, Sheldon Cooper said:

Just In Case of somehow missing it. 

 

Will probably only be high ground but who knows and of course there still is a chance that snow could still fall on low grounds just not as much. 

There is a chance of a period of heavy snow across this region; should it occur it is likely to cause significant travel disruption.

 

What to expect

There is a small chance of travel delays on roads with some stranded vehicles and passengers, along with delayed or cancelled rail and air travel

There is a slight chance that some rural communities, mainly those at higher elevations, could become cut off

There is a small chance that power cuts will occur and other services, such as mobile phone coverage, may be affected. - Met Office Warning

Also if you live in the Highlands

 

No poop.

[blitzen]

4 hours ago, Sheldon Cooper said:

4 hours ago, Sheldon Cooper said:

We can dream. 

-Best keep on dreaming!   That chart looks like a scene from the movie " The Day After Tomorrow !"  

 

Edited January 11, 2021 by Blitzen

[NorthernRab]

It's actually turning into a fairly heavy fall now. Big flakes. 

[Ruzzi]

I reckon there will be an Amber warning issued Tues night / wed morning provided the front continues to show signs of stalling in the right place. If everything backs west ever so slightly then Amber warnings will be nailed on 

[Norrance]

29 minutes ago, Quinach said:

Dreich.

Rain since 10am but now noticing a few flakes of snow, though still 95%+ rain so will refrain from the sleet classification!

Calm conditions and 3.1c, down from the 6.6c at 8:30am.

The temperature divide across scotland very obvious on the Met Office weather observation site - 

/Assets/Images/logo-global.png

Met Office WOW - Home Page

WOW.METOFFICE.GOV.UK

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The UK Met Office Weather Observation Website (WOW). WOW allows anyone to submit their own weather data, anywhere in the world.

 

That looks a bit weird on Lewis. 10C on one side and 3C on the other. Here still very much in the mild air at 9C. 5 degrees higher than any other day since the turn of the year. Clouding over now with a fresh Westerly.

Edited January 11, 2021 by Norrance

[Hairy Celt]

Rather annoyingly, the temp's gone up a tad and it's gone back to sleet just here  while sister up the hill gloats.

[mardatha]

Dry here and  not nearly cold enough for snaw.

[Hairy Celt]

And now it's raining. 

[Northern Strath]

Some guy on the dog walk was complaining about the snow we’ve had of late. Heretic. It’s beautiful to watch

 

[Scottish-Irish Skier]

1 hour ago, Hairy Celt said:

10p piece (not that I use them any more!) flakes coming down thickly now, just starting to settle on grass and cars. Evaporative cooling? 

No evaporation going on if it's chuckin it doon. 

It's endothermic cooling; the snaw needs heat (ΔH, enthalpy of fusion* / melting, = 333.55 J/g for ice-water) tae melt, so it's sucking it out of the surrounding air. It cools the surrounding air/water to/towards the ice melting temperature of 0 C until the melting process is complete.

It's why scientists use a bucket of melting crushed ice as a constant temperature reference / for probe calibration; it sits at precisely 0°C. We regularly check our cell probes by this simple approach. 

Evaporative cooling occurs when liquid water turns to vapour. For that, you need the air to be understaturated with moisture, encouraging evaporation. This too is an edothermic process, with enthalpy of vaporization needed to turn liquid water to vapour at constant temperature.  The opposite occurs with condensation; heat is released. But when ice finally nucleates, it will warm up again suddenly to zero C until freezing completes, when it returns to freezer temperature. Called an exothermic temperature spike. 

You can think of it as the energies needed to make the molecules go from tightly packed and all but stationary (solid ice) to moving around hitting each other (water), to very loosely packed and flying around in the air bouncing off each other (vapour).

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Enthalpy of fusion - Wikipedia

EN.WIKIPEDIA.ORG

Enthalpy of vaporization - Wikipedia

EN.WIKIPEDIA.ORG

 

Edited January 11, 2021 by Scottish-Irish Skier

[Hairy Celt]

1 minute ago, Scottish-Irish Skier said:

No evaporation going on if it's chuckin it doon. 

It's endothermic cooling; the snaw needs heat (ΔH, enthalpy of fusion* / melting, = 333.55 J/g for ice-water) tae melt, so it's sucking it out of the surrounding air. It cools the surrounding air/water to/towards the ice melting temperature of 0 C until the melting process is complete.

It's why scientists use a bucket of melting crushed ice as a constant temperature reference / for probe calibration; it sits at precisely 0°C. We regularly check our cell probes by this simple approach. 

Evaporative cooling occurs when liquid water turns to vapour. For that, you need the air to be understaturated with moisture, encouraging evaporation. This too is an edothermic process, with enthalpy of vaporization needed to turn liquid water to vapour at constant temperature.  The opposite occurs with condensation; heat is released. 

You can think of it as the energies needed to make the molecules go from tightly packed and all but stationary (solid ice) to moving around hitting each other (water), to very loosely packed and flying around in the air bouncing off each other (vapour).

---

Enthalpy of fusion - Wikipedia

EN.WIKIPEDIA.ORG

Enthalpy of vaporization - Wikipedia

EN.WIKIPEDIA.ORG

 

Obviously isn't fkn working seeing as it's fkn raining now. 

[Scottish-Irish Skier]

2 minutes ago, Hairy Celt said:

Obviously isn't fkn working seeing as it's fkn raining now. 

Lol.

Evaporative cooling is good for keeping yer snaw in tact. If the air is above zero but very dry, the snaw can't get the heat it needs to melt easily and tries to evaporate. This cools it through evaporative cooling, slowing the melting process.

Hence snaw in the alps lasts well in the sunny, crisp, dry conditions, even if it feels quite warm and you are eating your lunch outside in a t-shirt.

When the air is moist and warm like soggy Scotland, it carries a lot more heat to provide the deltaH for melting, so kills the snaw.

Edited January 11, 2021 by Scottish-Irish Skier

[Northern Strath]

2 minutes ago, Hairy Celt said:

Obviously isn't fkn working seeing as it's fkn raining now. 

Yer sister’s pad got an annex? 

[Hairy Celt]

3 minutes ago, Northern Strath said:

Yer sister’s pad got an annex? 

None that I'd kip in. Rotten roof tiles.

[Ravelin]

Do you think a front passed through? Lol Alternating between wet snow, sleet and rain so not lying, not at this altitude anyway. Still got the occasional small patch left that survived the thaw.

[JamesM]

Looking white even at low levels on the traffic cameras around the Inverness area. 
 

Form an “in my back yard perspective” hopefully the front on Wednesday stalls a bit to the west and doesn’t allow warmer air to be mixed in. If so, I could be in the game. 

[Eagle Eye]

Inverness webcam has heavy Snow at the moment brilliant.

Only one word to describe it snd that's beautifull.

Already laying as well.

[NorthernRab]

Aye I'm in Inverness city centre at sea level at the moment and it's been snow the whole time since it turned a few hours ago. 

[Swave Snow]

in aviemore the snow base became very wet and thawed a lot then rained really heavily and conditions were rather wet and icy then at around 12.45pm it turned to heavy snow and its still coming down giving a nice heavy snowfall in Aviemore 

[Northernlights]

An afternoon of snow and temperature of 0c.                            Seems to  be easing from the north now

[howham]

Alternating between rain, sleet and wet snow here depending on how heavy it is at the moment.

[mistyqueen]

Rain finally stopped. Temp started dropping away at lunchtime and is now down to 2.4c from 8.4c. Can really feel the difference now. Enjoy the snow, those of you who get it! 

[Northernlights]

2 hours ago, Northernlights said:

An afternoon of snow and temperature of 0c.                            Seems to  be easing from the north now

Treating some calves for infections this afternoon with an Austrailian vet who was more excited about the snow than I was something I haven"t seen before. The phone camera was well used!!!!!

[101_North]

Quite impressed at how we've avoided the rain so far today! 

If it was snow I'd be losing my mind about now

Edited January 11, 2021 by 101_North

[101_North]

27 minutes ago, 101_North said:

Quite impressed at how we've avoided the rain so far today! 

If it was snow I'd be losing my mind about now

Until I attempt a walk! Got about 500m's and the heavens opened  

Temp dropping away too. Down from 7c to 4.5c in the last 20mins. 

Edited January 11, 2021 by 101_North