ATPL Met Question

[kev2002]

Just went through a sample exam for NZATPL Met. One question asks for tropopause height and temp over a given location on a HI LEVEL SIG WX chart. Height wasn't a problem but damned if I could establish a temperature. I tried using the ROFOR's in the aim to get the ELR and therefore temp but I was way off. Any advice? The Trevor Thom manual has no explanation either.

Cheers

[swh]

kev2002,

More than likely you will have an additional chart which covers the area that has grid winds and temps on it.

Generally you will be asked to find mean winds along a route, height of the tropopause, freezing level, isa deviation etc.

Also need to know if they are using ISA, constant above 36090 ft, or JSA, -2 deg/1000' all the way up.

And remember sometimes the question will have the tropopause above FL360, so normally they will look for -56 deg C.

[OpsNormal]

My understanding of the tropopause is that it is where the temperature ceases to decrease in the troposhere and becomes a contsant -57degC.

Hope that helps.....

OpsN.

[kev2002]

There is a wind/temp chart included but it's for 250hPa (FL340). The tropopause height in question is FL530. Even with JSA The temp I get is way lower than the answer which is -79 by the way. This also throws ISA out the window. Oh well. I guess I just have to hope a similar question doesn't come up in the actual exam.

Thanks anyway guy's.

[swh]

Kev,

That height must be at or near the equator...

What was the temp at 340 ?

What cloud did they have, eg bkn FL130-400 ?

[flying ginge]

kev,

hope this gets to you in time! Anyway I've got the same sample paper (AMT10 R0??). Q.50 is it?

From the 250hpa (FL340) chart find -41 overhead YBTL. We already know the height ot tropopause is FL530 from SIGWX PROG chart ASIA HI. So simple calc to find difference. FL530-FL340=FL190. FL190x2'/1000FT = 38'DEGRESS.

-41@FL340-38'DEGREES=79'DEGREES.

So height is FL530 and temp is -79'degrees.

Good luck

[kev2002]

Thanks Flying Ginge.

I figured it out last night (after I found the ON switch for my brain!) A good lesson in using more that one source to get an answer (ie sig wx and wind/temp charts)

Big thanks to swh and OpsNormal too