Frost pocket suspected.....

[Flying Eye]

Hi folks,

It's slowly dawning on me that I might live in a frost pocket.

Mostly my temps track some local airfields pretty closely, but also commonly when temps are falling below say (guessing) 10c then mine might drop say 2 degrees further.

What are the signs that I could watch out for that would tell me more surely if I really am in a frost pocket?

[The QCC]

Install a wireless temperature monitor near your station.
Previously I had a Fine Offset station and made a solar fan cooled thermal shield for the sending unit.

I have since installed a Davis Vantage Vue and was somewhat concerned about the small thermal shield. So I purchased a reputable brand wireless temperature sensor and installed it in the fan cooled thermal shield just above the ground near the Davis station.

Apparently the Davis shield is quite effective as the temperature difference between the two device is between .4 - .6 °C.

Carl

[wd40]

I assume you are at a lower elevation than the other airports and such. If you are lower cold air sinks. orchards after to be careful of planting in a low spot to prevent frost from damaging blooms in the spring as an example.

Also make sure the elevation of your measuring device above ground conforms to the standards for your location.

[mcrossley]

I am in a similar situation where my lows are noticeably lower than the nearby Manchester airport and other PWS. I do find that my car thermometer confirms this, by driving a couple of miles away it registers a rise, and likewise at night it often drops as I approach our town. Strange as we are not lower than the surrounding area.

[Flying Eye]

I am in a similar situation where my lows are noticeably lower than the nearby Manchester airport and other PWS. I do find that my car thermometer confirms this, by driving a couple of miles away it registers a rise, and likewise at night it often drops as I approach our town. Strange as we are not lower than the surrounding area.

That's great, it really does sound quite similar to my situation in some respects, I now feel a bit more confident that this is very probably what is happening here. Thanks very much.

It's a bit tricky as, from searching, I have come to the thought that frost pockets are rather more an agricultural phenomena and somewhat less a meteorological one. It's not discussed very much as far as I have been able to discover.

[RayProudfoot]

Find out what type of soil is common in your area. Sandy and chalky soil retains far less heat than clay. Rickmansworth is a notorious frost hollow in the UK and so is Bournemouth even though it's close to the sea.

The area at the bottom of a long hill will also be colder. Woodford (SE of Manchester) recorded -18C in Jan 2010 but my station 3 miles away in a back garden recorded only -11C. Big temperature variations over small distances are common when it's cold.

[Flying Eye]

Interesting Ray,

You've caused some further thought in a slightly different direction.

I'm a little south of Milton Keynes and Bletchley, and as a result the moderately recent (say up to 25-35 years ago) local construction for miles around tends to feature gardens contained within a brick privacy screening arrangement to about 6 feet. It's perhaps not quite so common today but was when all of this building went on, and was also a rather popular feature in Victorian, and at a few other times down our national history line.

Anyway, the upshot of this is that it may not exactly be a frost pocket but perhaps more of a temperature lag pocket. Of course the wind would probably see all of this brick screening as some sort of gigantic and fun series of rat runs to howl around in, for want of a better description.

One of the sites I was looking over suggested that gardens behind brick walling is often where you might expect to find these sorts of effects. Since we have plenty of it, then it's presumably quite likely to feature in this way.

Has to be something like that, I must suppose.

[RayProudfoot]

Ian,

I'm certain that the temperature in a fairly enclosed space like a rear garden will be different to that in a nearby open space. Now how you interprete 'different' is uncertain. A sheltered garden might expect to experience a lower temperature on a clear night than an open space due to a lack of air movement but this will be negated by the warmth generated by nearby houses. Which has the geater effect? Hard to say.

You only have to look at temperatures on a windy day (or night) to see how little they vary. Still air, whether at night or day, causes the biggest temperature differences in equipment depending on 1) the conditions described above and 2) how well a sensor is shielded.

Looking back to your first post you raise the same point that I questioned when I first got a PWS and used the nearby stations at Manchester Airport and Woodford for comparison. Eventually I decided to ignore them because the environmental differences were so great. You probably should too otherwise you'll drive yourself batty trying to work out if your station is positioned optimally. Providing it's 4ft or so above the ground (preferably lawn), not near sources of heat lke walls etc. and is well ventilated the temperature you record will be accurate for YOUR environment. I emphasise YOUR environment because temperatures change so much over a short distance.

We all have micro-climates around our stations and unless we move all our kit to the middle of an open field these differences will still exist. Your readings are not wrong and it's doubtful you're in a frost pocket. I've given up now trying to use nearby sites as a reference. You'll probably benefit by doing the same. Check those stations' lows on a cloudy night and I doubt you'll see any differences to yours.

[Flying Eye]

You're quite right of course Ray,

Expecting our kit to exactly track other kit and even professional kit is quite probably a short cut to an asylum. However it was the different rate of change that caught my eye, and that's part of the process of me trying to learn about, and understand, my particular local environment a bit better.

I got into weather watching as the national or even nationally funded local forecasts ignore my area, they can only be working with a very old map and think there's no one here. Also I'm less interested in forecasting, and a good deal more interested in recording the weather around me where I live.

This is my best shot at gaining some relevant local data to work with as opposed to merely national averages and largely complex speculation.

Down the years I've come to the thought that the weather and what it is doing is quite possibly a state secret, so much so that we don't any of us realise it!

From my own recent experiences I'm starting to wonder if it's even legal for an individual to obtain and use a weather station!

[RayProudfoot]

Ian,

Do you upload to the internet? WUnderground would be useful as I could look at your temps for the day in question and compare to other nearby sites.

Publishing weather stats won't be illegal... yet! But if your station doesn't show signs of global warming you may have your equipment confiscated in the national interest!

You're not alone in feeling neglected. The BBC TV weather presenter stands in front of a large part of NW England as the view sweeps south and spends far too much time concentrating on the south!

[Flying Eye]

no Ray, no uploads yet, still finding my feet to my satisfaction. Once I get there I'll be happy to share my local findings with others.

As soon as I get a reliable working station it will help greatly of course. I've reached the upper end of what I feel having a weather station is worth to me, I simply can not justify spending any more on it than I have now.

If the worst comes to the worst I'll just add a rain gauge to my current thermometer and that will have to do. Won't be as nice as I had hoped, but it would suffice for a somewhat reduced level of interest! It'd be less for the weather station police to confiscate anyway!

One point about "the national average for this time of year" as they so often like to say; no one lives there! Am I the only one who has noticed this virtually pointless obsession they appear to have with it? What must they be spending to indulge that obsession?

Meantime I have a crummy part time "pro" station at an airfield NE of me! More or less 9-5 or pretty close to that. Surely getting that and others like it up to scratch could be a more sensible spend?

Sorry for the mini rant, but it does seem a fair point!

[RayProudfoot]

Hi Ian,

Going online makes it infinitely more interesting when you can share your info with others but I understand your reasons. Adding rain will make a big difference.

The Met Office use the "Central England Temperature" for long-term statistical reasons. It's a triangle covering central England furthest from the sea. I think you are just outside it but I can understand its purpose. Consider us up north when the press talk about a heatwave. They mean southern England and the SE in particular. We don't count!

That airfield station is probably on MoD land which is subject to severe spending cuts. Don't expect any improvements in this parliament!

[Flying Eye]

Hehe, it didn't see any improvement under any of the previous governments that I can recall either.

EGTC is attached (somehow or other, obscure) to Cranfield Institute of Technology, and it seems precious little good has come from that!

It's all a bit of a worry really!

[RayProudfoot]

And I think the Woodford site - EGCD - may soon become another victim. The Nimrod aircraft built there were demolished earlier this year in sight of the people who built them!

It's rumoured Hollywood studios are lining up to buy part of the site. Expect some "The Day after Tomorrow" weather readings in the future!!

[Flying Eye]

I'm sad to hear of the old ladies being wrecked, one of my favourites of all time. However in their case I think I can understand how foolish it could be to leave any of them laying around too casually! And much less the cargo that ran in them.

And as for Hollywood, I bet you they will never manage to make any thing as exciting as the planes that were made there.

Of course you realise I shall now have to go watch that old movie again! Oh well, who needs an early night!