crb wrote:
Andrew Gabriel wrote:
No, I get believable readings from clouds, typically -40 to -50,
which agrees with what aircraft report as the outside temperature.


Clouds at -40 to -50? - I don't think so. You have to go to around
30,000 feet or above to get down to those temperatures.

CRB

Sea level standard is ISA 15 deg. C and a lapse rate of 1. 98 deg. per
1000' you can work it out for yourself? Although in different parts of
the world the altitude temp does not always follow the formulae.