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Keith Dancey · October 7th 05, 04:11 PM posted to uk.sci.weather

In article , "Col" writes:

"Keith Dancey" wrote in message
...
In article , "Col"
writes:

I have to admit, I'm getting used to the graphics now.

Surely not? Not gone over to the "Dark Side"?

I find your lack of faith in the new graphics disturbing

It is bourne of experience...:-)

What about the mist? (Or is it fog??)

The mist/fog look the same as it did in the old system.

Why are the clouds depicted as shadows, even when seen from
hundreds of kilometers above, but mist is pale and obscuring? Why does
the rain always fall into giant floods?

Becasuse mist/fog obscures. We are generally affected by clouds by the
degree of shadow they cast, rather than the actual clouds themselves.
If the coulds are at ground level, they are called fog

But the view point is from hundreds of kilometres above the land surface,
so the new graphics uses *mixed* metaphors: clouds are transparent, but
cast shadows, while mist obscures. The difference between day and night
(the terminator) interferes with the metaphor for indicating cloud... When
is mist fog in this system? What is the indicator?

If you can keep an eye on your region and the time, following the
rain/cloud patterns for your area gives you a better 'feel' of the
expected progression of the day's weather than the old static
symbols ever could.

Aha! I carefully studied the animated cloud and rain patterns for my
region while on annual leave this summer. I had various activities from
which to choose, and the pattern and the timing of the day's weather were
of prime importance in that choice. Sunnier to the east, say, or to the
west? A strange finger of cloud to the south meant postponing that journey
for another time...

The reality bore no detailed resemblance at all to the graphics!

This was one of my initial criticisms of the system.

On a 'sunny intervals' type day I could see that there was a clear patch
above Bolton at 2pm, but at that time it could quite easily have been
cloudy. Was the forecast wrong?

But now I can see beyond interpreting every little dark patch as a
definite indication of cloud at that precise time and see it more as
another way of depicting 'sunny intervals'.

At this point I would repeat that the *danger* when using graphics which
are designed to impress the eye, is that they mislead on integrity. You
are FAR too wise and intelligent to take the displays literally, but they
are *designed* to be taken literally, and thereby mislead.

The resolution of the graphics far exceeds the resolution of the forecast,
and I suspect that, below the forecast resolution (both temporally and
spatially) the graphics play an entirely fictional element.

Unfortunately, because the graphics is designed to impress the eye, it
misleads on integrity. It is the victory of form over content (a bit like
the Tory and Labour Party Conferences) and a lot like "Government" today:-(

To be able to display the element of doubt would be the trick, which is why
"Mickey Mouse" weather symbols were so suitable: they implied an *idea* of
cloud within the area without being specific.

But so does the new system. The speckling of light/dark areas that means
sunny intervals means exactly that to the public.

Only us lot would pore over it and tut when the day's sunny cloudy spells
didn't exactly correspond to what was forecast

It is worse than that: on an otherwise dry day for the entire south of England,
Oxfordshire was shown with a giant puddle lasting at least an afternoon. It
didn't happen.

What are the public to make of that?

The display didn't say "a chance of rain"... "somewhere in the Midlands"...
It said "Oxfordshire was going to be a lake" that afternoon, but no rain
fell anywhere. The model cannot accurately predict down to that level, but
the blasted graphics can...

So when you see those detailed isolated puddles (floods) on this expensive
graphics system, pay no attention to the locality shown. It is not accurate!
It may be a counties' width wrong, or more...

Of course, when it comes to the matter of *timing* you need a chameleon's
eye to watch the clock in the bottom right-hand corner while noting the
animated changes going on to the far left! I'm only mildly surprised they
decided not to run the latest football scores along the bottom as well.

It's easy enough, and I live half way up the TV screen!

For those in the SE, the most important bit of course, it should be even easier.

But as I have already pointed out, it's the ebb and flow of the cloud/rain
or even the *idea* of cloud rain that is far better.
You simply never got that with the old symbols which at best gave an
indication of morning/afternoon/evening for a day's weather.
Take the front that has been lurking off NW Scotland all week.
The graphics have shown it moving nearer then retreating before finally
being forecast to move through on Saturday. Now under the old system you
would *never* have got that feeling of movement and ebbing and flowing.
The weather is of course a continuous process, not just conveniently
sliced into segments known as 'morning', 'afternoon', and 'evening'.

I am not going to argue that *animation* is not better than static displays.
But other Companies have managed to animate using stylised symbols which
do not carry the implied detailed accuracy which the BBC graphics system
does.

Symbols were invented in meteorology by some very clever people, and the
ones which survived the test of time did so because they worked.

Computational capabilities allow smoothe animation. But forecasting is
probability-based, so the trick is how best to represent those
probabilities in a dynamic fashion?

I say not with pseudo-realistic images because (a) they imply a certainty that
simply doesn't exist and (b) because there are meteorological indicators which
cannot be so represented (and which the BBC graphics, therefore, largely ignore).

A meteorologist would not design such a system: it is the work of people
with graphics skills (from gaming, no doubt!) who do not appreciate the
essential probabalistic nature of meteorology.

The BBC appear to have decided that the graphics engineers know best:-( It
is, what the Usanians would call, "eye candy". And to support the decision
the BBC must fall back onto the "public do not understand anything" argument.

All the best Col:-)

Cheers,

keith

---
Iraq: 6.5 thousand million pounds, 90 UK lives, and counting...
100,000+ civilian casualties, largely of coalition bombing...
London?...

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