Ice warning - in VMC, below freezing level
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Islander
My knowlege of met theory is negligible, but the following appears obvious - do say if you disagree:
From the skew-t, it's trivial to tell the cloudbase, the tops, the temperatures at various levels.
Everything else (or, more precisely, the effect of it on what you will actually encounter up there in terms of weather) is not so trivial, and that is the area where I would prefer to get an expert to do the interpretation - not least because a single skew-t is just one vertical line in space and weather does move horizontally rather a lot
One can tell the potential for freezing rain; however as this NASA paper suggests http://gltrs.grc.nasa.gov/reports/20...000-210058.pdf freezing rain traditionally results from snow falling through a warm layer in which it melts, and then falling through a freezing layer below, and I can't readily see how you are going to tell if there is going to be snow generated from somewhere above the warm layer. The only thing I know is that rule of thumb which is that if the thickness is within a range of so many decametres (520-530 or whatever) - one of many URLs is http://homepage.ntlworld.com/booty.weather/tthkfaq.htm - then precipitation should fall as snow. But how do you know there will be snow in the first place? So, to me, this simple method appears to generate excessively frequent freezing rain warnings - because such inversions are common.
The remaining difficulty with the skew-t is that the actuals are widely spread (obviously, they are the launch sites) and for some reason the forecasts are widely spread too - this site http://pages.unibas.ch/geo/mcr/3d/meteo/ (Animated Soundings) is the only one I know of. Common sense tells me that the GFS model contains absolutely everything that is needed to generate a skew-t for any point on the earth; whether it would have enough resolution to yield useful data for en route purposes is another matter because after all it is just interpolation from observations which are themselves widely spread.
So a skew-t is going to be just a useful tool, among many others like TAFs, METARs, the SigWX form etc etc.
As to syllabus, I am sure you are pulling my leg but my answer would be that it should be practical. Today, that means knowing how to get onto various weather data websites (and not just the one "CAA-authorised" one) and form a picture.
My knowlege of met theory is negligible, but the following appears obvious - do say if you disagree:
From the skew-t, it's trivial to tell the cloudbase, the tops, the temperatures at various levels.
Everything else (or, more precisely, the effect of it on what you will actually encounter up there in terms of weather) is not so trivial, and that is the area where I would prefer to get an expert to do the interpretation - not least because a single skew-t is just one vertical line in space and weather does move horizontally rather a lot
One can tell the potential for freezing rain; however as this NASA paper suggests http://gltrs.grc.nasa.gov/reports/20...000-210058.pdf freezing rain traditionally results from snow falling through a warm layer in which it melts, and then falling through a freezing layer below, and I can't readily see how you are going to tell if there is going to be snow generated from somewhere above the warm layer. The only thing I know is that rule of thumb which is that if the thickness is within a range of so many decametres (520-530 or whatever) - one of many URLs is http://homepage.ntlworld.com/booty.weather/tthkfaq.htm - then precipitation should fall as snow. But how do you know there will be snow in the first place? So, to me, this simple method appears to generate excessively frequent freezing rain warnings - because such inversions are common.
The remaining difficulty with the skew-t is that the actuals are widely spread (obviously, they are the launch sites) and for some reason the forecasts are widely spread too - this site http://pages.unibas.ch/geo/mcr/3d/meteo/ (Animated Soundings) is the only one I know of. Common sense tells me that the GFS model contains absolutely everything that is needed to generate a skew-t for any point on the earth; whether it would have enough resolution to yield useful data for en route purposes is another matter because after all it is just interpolation from observations which are themselves widely spread.
So a skew-t is going to be just a useful tool, among many others like TAFs, METARs, the SigWX form etc etc.
As to syllabus, I am sure you are pulling my leg but my answer would be that it should be practical. Today, that means knowing how to get onto various weather data websites (and not just the one "CAA-authorised" one) and form a picture.
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Originally Posted by MightyGem
Hmmm...how long has a tephigram been called a skew-t?
I found a good blank tephigram on the net if anybody wants to plot the soundings.
http://maths.ucd.ie/met/msc/PhysMet/blank_tephigram.pdf
This tephigram shows the dry adiabats as paralell straight lines, whereas the SALR is clearly temperature dependant (not fixed 1.5 C/1000ft as some texts imply) and approaches the DALR at high altitudes.
