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Is melted frost precipitation?


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Posted
  • Location: Nr Appleby in Westmorland
  • Location: Nr Appleby in Westmorland

I think I may have asked this before, but can't remember the answer if I did.

My rain gauge has recorded 0.2mm of rain today, which is obviously just melted frost from the past few nights finally tipping the balance (literally). Whilst a tiny amount, should this technically be recorded when I know for certain that it hasn't rained?

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey

How-do!

This may be a bit forward for my first post, but I'd say the answer to your question depends upon your use of the term Precipitation. In Chemistry, Precipitation is the process of separating a substance from a solution (which generally means the separation of a solid from a liquid, but can also include separation of a liquid from a gas).

In Meteorology, Precipitation usually refers to something that physically falls from the sky, be it rain, hail or snow, and the word itself is generally synonymous with "Rainfall".

Do you include dew in your precipitation totals? If so then melted frost should be included, too. If dew isn't counted as precipitation since it doesn't "fall from the sky", then nor should frost be.

Hope this helps, and that I haven't rambled on too long!

PS - Love the site, love the forum - been reading a long time but never signed up before. I look forward to some great threads over the coming Winter!

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Posted
  • Location: Nr Appleby in Westmorland
  • Location: Nr Appleby in Westmorland

Thank you Sir,

I include whatever my rain gauge registers, and it's possible that some mornings when it shows 0.2mm, it could have been from dew. It's just, at the moment, I know for certain we've had no rain.

Your logic therefore is perfect, and it will go on my spreadsheet.

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Posted
  • Location: Upper Tweeddale, Scottish Borders 240m ASL
  • Location: Upper Tweeddale, Scottish Borders 240m ASL

And a hearty welcome to posting on the Forum Captain :D

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey

Thanks for the welcome! This is pretty much the only board I've consistently enjoyed reading. so it's nice to join in and be welcomed.

I've been reading the forecasts and discussions on here for over a year now, and I'm STILL new at this forecasting lark, can't say I can make head nor tail of the charts, and wouldn't even attempt to give predictions for the future. However, if I see anything I can add intelligently to (which is probably quite unlikely!) then I'll put my oar in!

See you round the boards!

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey

Well....if you insist!

Everton Fox and the Met Office are going for mild, mild, mild, so - just for a laugh - I'm going to suggest it'll be pretty nippy, starting around the 2nd week of December and continuing non-stop until the third week of February. I have absolutely no scientific evidence to back up these claims...

Absolute bobbins, I'll grant you, but writing it out like that is very satisfying, isn't it?!

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Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

When we had the Met office checking our site one of them said that melted frost and dew dripping into the rain guage count towards the months rainfall.

And if you had a hard frost that melted in the night and then it rained how would you remove it from the total????

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Posted
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey
  • Location: A small planet somewhere in the vicinity of Guildford, Surrey

Good point. I was making a somantic (or should that be pedantic?!) argument, but you're quite right. Similarly I suppose fog could trickle its way into the gauge overnight and be counted as rainfall, too, despite not having actually fallen as rain.

When talking about rainfall totals I suppose it's best just to count anything that collects in the gauge that's wet!

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Guys,

According to wikipedia (which I know doesn’t necessarily mean a great deal),

“Precipitation is any product of the condensation of atmosphereic water vapour that is deposited on the earth's surface”.

So I suppose by that definition it should be included then?

Following on from that, are the tipping bucket type rain gauges accurate for hail and snow or not?

Regards,

Garth.

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Posted
  • Location: NH7256
  • Weather Preferences: where's my vote?
  • Location: NH7256
Guys,

According to wikipedia (which I know doesn’t necessarily mean a great deal),

“Precipitation is any product of the condensation of atmosphereic water vapour that is deposited on the earth's surface”.

So I suppose by that definition it should be included then?

Following on from that, are the tipping bucket type rain gauges accurate for hail and snow or not?

Regards,

Garth.

no cos unless it melts before the funnel is full, any fresh snow just blows away.

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Posted
  • Location: Derbyshire Peak District. 290 mts a.s.l.
  • Weather Preferences: Anything extreme
  • Location: Derbyshire Peak District. 290 mts a.s.l.
I think I may have asked this before, but can't remember the answer if I did.

My rain gauge has recorded 0.2mm of rain today, which is obviously just melted frost from the past few nights finally tipping the balance (literally). Whilst a tiny amount, should this technically be recorded when I know for certain that it hasn't rained?

The answer to this is definitely, yes. According to the Met' Office's Observers Handbook any precipitation in the gauge, be it from rain, snow, hail, dew, frost or fog should be recorded. If it's known that no rain has fallen a note should be made in the log as to the origins of the precipitation.

Up here on the moors a persistent thick fog will frequently produce between 0.2mm and 0.4mm of precipitation, even when there's no drizzle to accompany it, and hoar frost can give 0.1 or 0.2mm.

I've never separated out the total annual amount of precipitation from sources other than rain but over the course of a year I would think (here ) between 3 and 8 mm would result.

T.M

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