minus temp no frost

Post Reply
User avatar
flounder
Posts: 5617
Joined: Mon Dec 20, 2010 5:16 pm
Location: brighton

minus temp no frost

Post by flounder » Thu Feb 02, 2012 11:52 pm

Some one please explain this phenomena to me. Temps got down to -2.4c ish but no frost on windscreen or grass as I usually see.
I know it must be to do with relative humidity and stuff, but would like a concise and lucid explanation
ta
my name is flounder, but you can call me.............flounder! (or Gary, just don't call me late for dinner)


User avatar
billdango
Posts: 2854
Joined: Mon Jan 31, 2011 9:12 am
Location: southampton

Re: minus temp no frost

Post by billdango » Thu Feb 02, 2012 11:59 pm

flounder wrote:Some one please explain this phenomena to me. Temps got down to -2.4c ish but no frost on windscreen or grass as I usually see.
I know it must be to do with relative humidity and stuff, but would like a concise and lucid explanation
ta
It was the same here in Southampton last night?

_3c and not a hint of frost.

I think the humidity was rather low so that was the reason.

rgds Billdango


User avatar
GoggleboxUK
Posts: 16877
Joined: Fri Mar 04, 2011 9:58 pm
Location: Preston Lancashire

Re: minus temp no frost

Post by GoggleboxUK » Fri Feb 03, 2012 12:07 am

If the temp doesn't get as low as the dewpoint you won't get frost because no moisture is formed on surfaces to freeze and turn all sparkly white.

It can be minus 6 but if the dewpoint is -8 then the air is dry and cold rather than wet and cold.

Don't make the mistake of thinking ground frost is frozen surface water, it isn't. It's the dew formed by the condensation process that occurs when the air temperature and the land surface temperature are at odds and condensation occurs then freezes.

I learned that off Stephen the other day so just passing it on. Blame the teacher if I've got it wrong :lol:
Once upon a time there were 3 little bears. Now there's thousands of them.


User avatar
flounder
Posts: 5617
Joined: Mon Dec 20, 2010 5:16 pm
Location: brighton

Re: minus temp no frost

Post by flounder » Fri Feb 03, 2012 12:11 am

Right thanks guys, they were the answers I expected. Just wanted clarification icon_thumright
my name is flounder, but you can call me.............flounder! (or Gary, just don't call me late for dinner)


Conifers
Posts: 13147
Joined: Sat Jun 20, 2009 2:11 pm
Location: Northumbs

Re: minus temp no frost

Post by Conifers » Fri Feb 03, 2012 12:16 am

Was the soil hard and puddles frozen?


GREVILLE
Posts: 2866
Joined: Sat Jan 22, 2011 10:39 am
Location: South London

Re: minus temp no frost

Post by GREVILLE » Fri Feb 03, 2012 12:17 am

Low humidity, low frost. My humidity levels were down to 34% today. Driving home at 11pm tonight no frost to be seen anywhere. My weather station told me -3c and 67% humidity. It's always higher at night but that level is still too low for frost on vehicles. You might see a little on the grass as, holding moisture, it will be more humid at ground level.


User avatar
flounder
Posts: 5617
Joined: Mon Dec 20, 2010 5:16 pm
Location: brighton

Re: minus temp no frost

Post by flounder » Fri Feb 03, 2012 12:18 am

Conifers wrote:Was the soil hard and puddles frozen?
yes and no because there weren't any puddles
my name is flounder, but you can call me.............flounder! (or Gary, just don't call me late for dinner)


User avatar
Mr List
Posts: 5075
Joined: Thu Jan 20, 2011 9:00 pm
Location: Leeds,West Yorkshire

Re: minus temp no frost

Post by Mr List » Fri Feb 03, 2012 7:50 am

does the lack of frost make any difference to plant damage at any given temperature
ie
-6 with frost is worse than -6 without (or visa versa)


User avatar
The Codfather
Posts: 6436
Joined: Tue Sep 07, 2010 6:02 pm
Location: Darlington, C.O. Durham

Re: minus temp no frost

Post by The Codfather » Fri Feb 03, 2012 8:04 am

Mr List wrote:does the lack of frost make any difference to plant damage at any given temperature
ie
-6 with frost is worse than -6 without (or visa versa)
I have have had - 6 with frost last night ! :(
AKA - Martin

Wish list - Big Palms or Dicksonia antarctica's but open to anything really.....Cash Waiting !


User avatar
kata
Posts: 14589
Joined: Mon Feb 22, 2010 10:03 pm

Re: minus temp no frost

Post by kata » Fri Feb 03, 2012 8:13 am

Wrap up Coddy............ :lol: :lol:
http://flowersnpalms.com/floraandfaunauk/

Rain...nowt but rain...Welcome to Lancashire............ :lol: :lol: :lol:


User avatar
Dave Brown
Site Admin
Posts: 19730
Joined: Sun Jul 09, 2006 10:17 am
Location: Chalk, (Thames Estuary) Kent, England 51.5N 0.3E
Contact:

Re: minus temp no frost

Post by Dave Brown » Fri Feb 03, 2012 8:24 am

We get these cold dry NE winds here periodically every late winter and spring. The main problem apart from wind chill factor is the low humidity, which then desicates the ground and plants. I'll be out there dousing the Dicksonia antarctica down as soon as this freeze is over..... provided I'm not under 6 feet of snow that is :lol:
Best regards
Dave
icon_thumright
_________________________________________________
Roll on summer.....
http://www.hardytropicals.co.uk


User avatar
Exotic Life
Posts: 1818
Joined: Fri Feb 16, 2007 3:03 pm
Location: Southwest of the Netherlands

Re: minus temp no frost

Post by Exotic Life » Fri Feb 03, 2012 10:25 am

No very humid here as well with the lowest point yesterday with just below 30%. It's swinging between the 30-40% since the cold started. Lows between the -5/-10 and windchills till -20C. Now I do know again why I hate winter...

But at least no frozen car windows as well. :)


User avatar
cordyman
Posts: 7129
Joined: Mon Aug 17, 2009 10:24 pm
Location: Northwest UK

Re: minus temp no frost

Post by cordyman » Sat Feb 04, 2012 2:21 pm

Mr List wrote:does the lack of frost make any difference to plant damage at any given temperature
ie
-6 with frost is worse than -6 without (or visa versa)
i'd like to know this too!


I had over -4*c last night and ground didnt have a trace of frost, but car did have a little frost on the windscreen, but side windows were all clear.


Post Reply