Sat Jul 22, 2017 7:52 pm
#1548168
Ugh
thought I understood this, turns out I don't.
So, from Pooley's Air Pilot's Manual on Meteoroogy:
"On a given day the sea level pressure is 1013.2 hPa. The temperature at 3,000ft AMSL is given as minus 4C. The temperature difference compared with the ISA is ... "
I'd thought from what I'd read that for every 1,000ft increase in altitude the temperature would be expected to decrease by approximately 2C. Which would mean that at 3,000ft we would expect the temperature to be 9C, the fact that it's actually -4C would therefore mean that the differential is ISA (9 at that altitude) - 13 (to get to the -4C).
The book answer though is that the differential is ISA - 10. Which I just don't get at all. If they mean 15 - 10, then that doesn't work. If they mean 9 - 10 then that doesn't work either.
There must be a glaring error in my understanding of the question, some issue with my maths, or a problem with the book answer. I can't work out which it is though
If someone could explain the correct answer to me I'd appreciate it. Thanks
thought I understood this, turns out I don't.
So, from Pooley's Air Pilot's Manual on Meteoroogy:
"On a given day the sea level pressure is 1013.2 hPa. The temperature at 3,000ft AMSL is given as minus 4C. The temperature difference compared with the ISA is ... "
I'd thought from what I'd read that for every 1,000ft increase in altitude the temperature would be expected to decrease by approximately 2C. Which would mean that at 3,000ft we would expect the temperature to be 9C, the fact that it's actually -4C would therefore mean that the differential is ISA (9 at that altitude) - 13 (to get to the -4C).
The book answer though is that the differential is ISA - 10. Which I just don't get at all. If they mean 15 - 10, then that doesn't work. If they mean 9 - 10 then that doesn't work either.
There must be a glaring error in my understanding of the question, some issue with my maths, or a problem with the book answer. I can't work out which it is though
If someone could explain the correct answer to me I'd appreciate it. Thanks