Cloud Top height
 

Does anyone know if there is a standard colour representation for cloud
top charts/images up to 16.8kms.

Cheers,
James
--
James Brown

Cloud Top height
 

"James Brown" wrote in message
...
Does anyone know if there is a standard colour representation for
cloud
top charts/images up to 16.8kms.


.... I see no-one has replied; possibly because, like me, we're not sure
what you mean ;-)

If you mean is there a standard for colour-slicing of Infra Red (or
indeed any imagery) on workstations, then AFAIK, there isn't. All the
systems I have worked on in the past let you define your own set-up for
colours, depending upon the temperature of the cloud tops. Indeed, many
let you store your own default set-up. I used to find it useful to have
a particular scheme just for cold tops (roughly colder than -30degC), so
that anything colder was a shade of blue or green, with all other set to
grey-scale. You could then tell instantly whether areas of cold topped
cloud were growing (developmental) or decreasing (weakening). Another
useful dodge for night-time was to try and 'tune' the colours of SC/ST
against the land surface - didn't always work of course, but even a
slight difference, when run on a rapid looping cycle, could help decided
where a Sc edge was going. There are many variations on this theme.

Some standard visualisation packages may offer 'default' schemes, but
even these can often be tinkered with.

In monochrome, then of course it has usually been 'standard' for
low-level / warm-topped clouds (e.g. St, Sc) to be dark grey to
near-black, whilst higher-level / cold-topped clouds (e.g. Ci, Cs) to be
white, with very cold (e.g. deep/vigorous Cb tops) the whitest of all.
But even this is not set in stone: it's just how things were done when
APT was first provided as an operational tool back in the 1960's.

HTH

Martin.

--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

Cloud Top height
 

In message , Martin
Rowley writes

"James Brown" wrote in message
. ..
Does anyone know if there is a standard colour representation for
cloud
top charts/images up to 16.8kms.


... I see no-one has replied; possibly because, like me, we're not sure
what you mean ;-)


Many thanks for that Martin. I should perhaps have explained that
EUMETSAT are issuing revised format CTH images - via their DVB
distribution system, derived from MSG-1 imaging. They actually give
heights rather than temperatures, though possibly there is some direct
correlation?

Cheers,
James
--
James Brown

Cloud Top height
 

"James Brown" wrote in message
...

Many thanks for that Martin. I should perhaps have explained that
EUMETSAT are issuing revised format CTH images - via their DVB
distribution system, derived from MSG-1 imaging. They actually give
heights rather than temperatures, though possibly there is some direct
correlation?


.... are these the ones?

http://makeashorterlink.com/?L2EC12077



Martin.

Cloud Top height
 

"Martin Rowley" wrote in message
...


... are these the ones?

http://makeashorterlink.com/?L2EC12077


.... since the above, have now had time to look on the EUMETSAT site.
Have a look at:-

http://makeashorterlink.com/?S53F35177

which states that the height information is derived from IR (averaged
over pixels) irradiance - i.e. based on temperature. (It did cross my
mind that with the wonderful sensors around nowadays, some sort of
radar-based imagery might be employed, but thinking about it, the
Meteosat (& other) geostationary series are probably too far out for
meaningful data. Polar orbiting platforms are another matter though.)

These products have been around for at least 10 years; we used to use
them at Strike Command in the early 1990's, when the products were seen
via 'wetfax' systems - only 4 times a day (as now), but still quite
useful as long as the lack of resolution was allowed for.

Follow the embedded link (CTH) from the EUMETSAT entry above, and you
will find a colour-chart which goes with the imagery. Perhaps this is
what you were after?

HTH

Martin.
--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm

Cloud Top height
 

Many thanks for that Martin - a useful link I had overlooked.

The latest images via MSG-1 have for example vegetation indexes for CLAI
images and the CTH with images which are now 1280 x 1392 and are 8 bit
deep. The area covered has also been extended so that the northernmost
extension e.g. is to Iceland.

Lots more goodies to come.

Cheers,
James


--
James Brown