The weather thread

Ye can keep yer auld tephigrams.

I had the blissful pleasure of driving through the snowy Wicklow Gap yesterday afternoon. I don't think I've ever seen anything quite so beautiful as the water rushing downhill over the rocks in the valley just outside Glendalough, surrounded by snowtopped trees and mountains.

You're an adventerous woman, Kate P. Ms AA Roadwatch was encouraging people to avoid that neck of the woods.

Not really. The Sally Gap was impassable but the Wicklow Gap was more or less okay (with only a few scary moments!) and it was a gloriously sunny afternoon. There were other drivers out, natives, I'd imagine and when I didn't have the road to myself to mosey along carefully and take in the view, I pulled up to let others past - all of whom were haring along the byways.

It was one of those breathless, 'I could die happy now' experiences.

On with the adventuring!!

Why don't you ask Papal Kmight. He is the expert with numerous advanced degrees.

Now even though it would reduce carbon dioxide, please do not hold your breath because he is just full of moosematter.

Ha ha ha ha ha ho ho ho.

youngdan wrote:

Why don't you ask Papal Kmight. He is the expert with numerous advanced degrees.

Now even though it would reduce carbon dioxide, please do not hold your breath because he is just full of moosematter.

Ha ha ha ha ha ho ho ho.

I was going to send the Canadian Mounties and a St. Bernard dog off to find you. Are you still perishing over there ?

Did you get the bale of briquettes we sent ?

Can anybody suggest something I can do to protect my face save wrapping my head in my scarf and looking like Peg Sayers?

Go for it. A dilution will occur allright. There is a lot to be said for the single life.

cookiemonster wrote:

Can anybody suggest something I can do to protect my face save wrapping my head in my scarf and looking like Peg Sayers?

I'm going to whisper, because I'm not sure you'll like either of these alternatives.

a balaclava (which I don't think would suit you, by the way)

A really, really good moisturiser with sunblock. Dermalogica do the best ones, imho after years of searching. I think they also do a men's range.

cookiemonster wrote:

Can anybody suggest something I can do to protect my face save wrapping my head in my scarf and looking like Peg Sayers?

When I lived in Canada, you could get these neck warmer thingys that were about 3/4 of a foot in length and elasticated wool, you could pull them up so they'd cover the lower half of your face and your neck, then you'd put a toque (hat) over your head. Can be used to just leave eyes exposed, then if it's really cold ,<-15, apply ski goggles. Result; no exposed skin.

See, it depends if you prefer Scott of the Antarctic to Peg Sayers as a fashion statement

Sadly, I've never seen the neck warmers here, although since I still have the Canadian ones, I haven't ever looked. Try Great outdoors, or similar, anywhere that sells ski gear??

Just in from the schools rugby... it was bitter out there. Thank goodness for the cup of tea in a friend's house around the corner afterwards.

That is a stinking lie. It was 0.4 degrees above what it was in 1850.

What is wrong Audi. Did the lad, Papal Kmight, that knows it all with the advanced degrees not pm you an explanation. Surely he can read a simple graph. It is beyond me as I only have an engineering degree

Youngdan
Papal has a very different mind to you and as an engineer this should be the type of thing which might interest the kind of mind you have if you liked engineering surely. Did you ? What did you used to or do you engineer by the way ?

Toxic and I have previously quoted places with information on this beast of a graph and I'm going to look at it now and again to see if I can figure anything out at all about it. I think it might be like one of those secret pictures which you only see with a little bit of practice. Or a map which you can read like a children's book once you know. Or a foreign language ..etc...

The only thing I've realised by now I think is that the red lines are constant (I think!) so it provides a background to the blue lines but I don't know what they mean. I'm inclined to think it's a plot of temperatures and pressures over some period of time ??


This from the Met Eireann link above:

Quote :

On the tephigram there are two kinds of information represented:

The environment curves (blue) which describes the structure of
the atmosphere
The process curves (red) which describes what happens to
a parcel of air undergoing a particular type of process.
(eg. Adiabatic
process).

In addition, the right hand panel displays height, wind direction, speed
and a selection of pressure levels.

Tephigrams can be used by the forecaster for the following purposes:

- to determine moisture levels in the atmosphere
- cloud heights
- to predict levels of convective activity in the atmosphere
- forecast maximum and minimum temperatures
- forecast fog formation and fog clearance

Quote :

A tephigram is a graphical representation of observations of pressure, temperature and humidity made in a vertical sounding of the atmosphere. Vertical soundings are made using an instrument called a radiosonde, which contains pressure, temperature and humidity sensors and which is launched into the atmosphere attached to a balloon.

The tephigram contains a set of fundamental lines which are used to describe various processes in the atmosphere. These lines include:

Isobars - lines of constant pressure
Isotherms - lines of constant temperature
Dry adiabats - related to dry adiabatic processes (potential temperature constant)
Saturated adiabats - which are related to saturated adiabatic processes (wet bulb potential temperature constant).

Quote :

A tephigram is one of four thermodynamic diagrams commonly used in weather analysis and forecasting. The name evolved from the original name "T-φ-gram" to describe the axes of temperature (T) and entropy (φ) used to create the plot. Usually, temperature and dew point data from radiosondes are plotted on these diagrams to allow calculations of convective stability or convective available potential energy (CAPE). Wind barbs are often plotted at the side of a tephigram to indicate the winds at different heights.
The tephigram was invented by Napier Shaw in 1915 and is used primarily in the United Kingdom and Canada.
Other countries use similar thermodynamic diagrams for the same purpose
however the details of their construction vary. In the tephigram, isotherms are straight and have a 45 degree inclination to the right while isobars are horizontal and have a slight curve. Dry adiabats
are also straight and have a 45 degree inclination to the left while
moist adiabats are curved. The principal reason that tephigrams are
used by the British Met Office
is the property that areas contained by the curves have equal energies
for equal areas, leading to better comparisons of CAPE and hence
convective systems.

They have a good illustrated example of one there too.
http://en.wikipedia.org/wiki/Tephigram[/quote]

Auditor #9 wrote:

Youngdan
Papal has a very different mind to you and as an engineer this should be the type of thing which might interest the kind of mind you have if you liked engineering surely. Did you ? What did you used to or do you engineer by the way ?

Toxic and I have previously quoted places with information on this beast of a graph and I'm going to look at it now and again to see if I can figure anything out at all about it. I think it might be like one of those secret pictures which you only see with a little bit of practice. Or a map which you can read like a children's book once you know. Or a foreign language ..etc...

The only thing I've realised by now I think is that the red lines are constant (I think!) so it provides a background to the blue lines but I don't know what they mean. I'm inclined to think it's a plot of temperatures and pressures over some period of time ??

I have e-mailed Met Eireann to try and get more information on what the axes and the broken and unbroken blue lines are saying. It's bugging me now, because it looks great, but I can't get my head around it. Here's hoping they come back to me with a coherent response....

Audi. A civil engineer. I have had many jobs. I like selling things. Anything from a woman to a washing machine.

Ok, this is the reply I got from Met Eireann (they're very good, they replied within hours). Thanks to Met Eireann...

Quote :

I refer to your query below. Many different atmospheric variables
essential to forecasting can be calculated from the tephigram. These
inlude stability indices, thunderstorm likelihoods, inversions, how
quickly thunderstorms are likely to develop in the day, cloud base
heights and many other vairables. The tephigram shows a moist layer
and a dry layer - where the two dark lines are closer together, the
more moist the atmosphere, the further apart, the drier the atmosphere.
Needless to say, it is difficult to explain in a couple of pages
exactly how these variables are calculated. Tephigrams are mainly be of
interest to pilots and meteorologists.


As detailed in the web page the four lines describe the various processes in the atmosphere.


Isobars - lines of constant pressure, on the left hand side and run parallel, starts with 1050 and rises to 200.

Isotherms - lines of constant temperature, lines skewed at 45deg.

Dry adiabats - related to dry adiabatic processes (potential temperature constant), lines skewed at 45 deg.

Saturated adiabats - which are related to saturated adiabatic processes, curved lines to left.


The unbroken blue line is the temperature as we climb through the atmosphere and the broken blue line is the dew point.


You will find more detailed explanations on any 3rd Level Meteorology books or from articles on the web.

I thought Pax, Ibis and Papal Kmight were holders of numerous advanced degrees in this field and they could not explain a simple graph to you. How very strange

youngdan wrote:

I thought Pax, Ibis and Papal Kmight were holders of numerous advanced degrees in this field and they could not explain a simple graph to you. How very strange

It's anything but a 'simple' graph...

From the link below:

Quote :

A "tephi" what ? If you are a pilot or a meteorologist, you are about the only people on this planet able to decipher this very useful chart.

http://shum.cc.huji.ac.il/~cariel/climate5763/tephigram.html

It is a simple graph. The man from Met even says that it is explained in any 3rd level Meteorology books.

They are claiming not just having a degree but a Masters degree on top of it. Papal Kmight even claims numerous advanced degrees. They must be in knitting and cooking because they sure any not in science or economics

Fair play to Met Eireann now - I wonder was it Jean Byrne who replied to your email ? She puts the "therm" into "isotherm".

I generally prefer the weather when it's dry - especially in winter. The quote below shows what to look out for if you're sensitive to humidity.

I also put some of the info into the screenprint below and we'll collect more there as it turns up. I don't know which reading is which on the x and y - which one is the adiabat and which the isotherm and which is the dew measure etc. I recognised the pressure I suppose. I'm getting the image of it being a map of the air conditions from the ground (bottom of the graph) to the top of the atmosphere or as high us as their sensors go or need to go (top of the graph). After that ..

Quote :

The tephigram shows a moist layer and a dry layer - where the two dark lines are closer together, the more moist the atmosphere, the further apart, the drier the atmosphere.

It seems to say that today was a relatively dry day for pilots. The other graphs show a zig-zagging divergence between the broken and unbroken blue lines all the way up, but on today's one there is a fairly constant divergence once you get above a certain point (perhaps above cloud level, today was relatively sunny) before a re-convergence at icier higher levels. So, to extrapolate, the more smooth the divergence and re-convergence, the fairer the day, the more zig-zaggy, the cloudier and wetter the day? I'm making this up off the top of my head, I'll see if it stands up over the next few days...

EDIT- it wasn't Jean whatshername, it was a chap called Aidan. Sorry...

I'm also going to guess that the numbers across the top of the graph are percentages - relative humidity ??? So the zig-zagging of the broken ----- dewpoint line means the variations in humidity from the bottom of the world to the top of the world. That broken line will refer to those percentages. Today's graph goes off the screen to the left for the dewpoint so it was just very dry at that pressure/altitude.

The numbers across the bottom I'm going to guess are temperatures - we'll know this for sure as we move into the summer where the unbroken ______ temperature line should move slightly towards the twenties if we're lucky. The unbroken line then refers to the numbers across the bottom.

Aidan Nulty was it ? Damn

Auditor #9 wrote:

I'm also going to guess that the numbers across the top of the graph are percentages - relative humidity ??? So the zig-zagging of the broken ----- dewpoint line means the variations in humidity from the bottom of the world to the top of the world. That broken line will refer to those percentages. Today's graph goes off the screen to the left for the dewpoint so it was just very dry at that pressure/altitude.

The numbers across the bottom I'm going to guess are temperatures - we'll know this for sure as we move into the summer where the unbroken ______ temperature line should move slightly towards the twenties if we're lucky. The unbroken line then refers to the numbers across the bottom.

I think that second stuff about temperature, on second thoughts, is a load of my boll***s.

It was a mild-ish day here thanks bit of God.

I'm not sure the number at the bottom of the red line isn't temperature as at 300 (on the right hand side) you can see the thicker blue line swings down to -5 although in the image below it seems that the temperature really high up at 200 isobars is about +20ºC - could that be true if what I'm thinking is right and it's an image of altitude ? Maybe during the day it could but at night it would be a lot cooler ...

There's supposed to be a lot more heat up there too when there's more CO2 up there ...