Hi there,
I’ve come across this nice little graphic of a colourised IR cloud image that is very up to date. I know Achim’s super GRAMET simplifies all this, but I would like to refer to the more experienced members here to help me read this graphic:
http://meteo-mc.fr/satellite-ir-anime-eu.php
Do you guys start with the surface temp and then use the standard lapse rate to work out the cloud heights or do you use GFS temps aloft data? I find it tricky as the frontal systems will have a sharp temperature change whereas I imagine the above would work okay for airmass clouds. Maybe a broad discussion on tricks to simplifying the interpretation of IR images and some worked examples would be beneficial.
DMEarc
Note: I have added here a GRAMET graphic which “forecasts” clouds in the west of Ireland front to the troposphere circ FL320 with temps at cloud tops of -52C.
There is a big difference between GRAMET and the IR sat image: the former is a forecast, the latter an actual picture with no uncertainty attached to it.
I recommend sat24.com which translates the temperatures to altitude values, that’s a bit more intuitive:
Note that the satellite only measures the temperature of the cloud tops. It has no idea what is below. Very thick cirrus clouds can show as a solid cover even though there are like 25,000ft of clear air below them. The sat IR image is most useful when your strategy is to remain on top of all clouds and you want to find out whether you will manage to do this (Peter is a proponent of this approach).
If you don’t insist on being on top for the entire flight, then GRAMET and TAFs are best to prepare and then rain radar and METARs shortly before the flight.
How did you get the altitude information? I don’t get that info even though I’ve checked “Altitude”.
This article is worth a quick read.
In short, there is no way to get the tops altitude directly, AFAIK.
For Europe, all the IR images come from EUMETSAT which as per standard European practice charges for it, despite the data being obtained using taxpayer money 
And they prohibit republication of anything really useful. Only commercial weather repackagers get access to the real time stuff and they pay a lot for it (4 digits a year is the starting point, AFAIK).
SAT24 is the main source now, for the 15 minute image.
Now, for altitude you first need the colour temperature of the IR image, which EUMETSAT do supply. Then you need the temperatures aloft and then you could produce an altitude chart against which one could match up the colour (or shade of grey) of any particular point. But AFAIK only one site in Turkey was doing that and that was 6 hours behind.
The way I use the IR image (see my writeup above) is as a rough guide, and in the context of TB20 altitude performance (FL200 in ISA conditions IF you can climb up there without getting iced up on the way up) one doesn’t need to be accurate to better than a few thousand feet. I don’t think there is any product available to the public which gets better than that.
And as Achim says you can get misled by high altitude cloud. But usually that possibility is apparent from other data. Cirrus cloud is often in regular strips which show as such on the IR image. Also if you get a large area on the MSLP then a large even area on the IR which shows as very cold is probably very high altitude cloud (not not always; I have seen solid IMC from the deck all the way to FL350 which was pretty rough in a 737, with no fronts anywhere near).
If you want accuracy then you need stable conditions (usually a widespread high pressure) and then you can usefully use the 0000Z or 1200Z Unit of Wyoming wx baloon data. Achim’s EuroGA autorouter wx briefing now gives you those. See my Dortmund trip thread for a really good example.
Now, for altitude you first need the colour temperature of the IR image, which EUMETSAT do supply. Then you need the temperatures aloft and then you could produce an altitude chart against which one could match up the colour (or shade of grey) of any particular point. But AFAIK only one site in Turkey was doing that and that was 6 hours behind.
Sat24 now do it for you. See earlier posts.
OK, true, but I never found those cloud top heights to be at all accurate.
Bear in mind that the 6km mark is the TB20’s ceiling (I know your turboprop can go to FL300, nearly) and the chart is no good for low cloud like in the last few days.
Their 2km lowest mark is plenty enough cloud to collect inches of ice and plummet 
The question is if the sat24 algorithm uses any information about the atmosphere’s current conditions to depict the altitudes or some standard approach (ISA).
A product using IR colors and the latest balloon ascends to accurately estimate the cloud top altitude would be quite powerful. autorouter would do this if the EUMETSAT image was actually available…
I have a very vague recollection of somebody digging into a site doing that (possible one of the Univ of Granada ones like OGIMET) and discovering the cloud top altitudes given were calculated in a completely wrong way. I seem to remember it was using just the ISA profile, which is reasonable for a non-pilot using google but totally useless for flying.
A product using IR colors and the latest balloon ascends to accurately estimate the cloud top altitude would be quite powerful.
The challenge would be determining when the baloon data is useful. 11th and 12 Feb, UK to Germany, yes
I agree the way they do it is not very granular and may be difficult to use for lower altitudes.
One thing I have never learned to do is to estimate cloud tops from Satellite Images. How is this done? Like many here I use Gramet and other tools like the profile view on many weather sites like Meteo Blue to get an idea, but what is the “best” way?
