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Coldest Outside Air Temperature At Altitude  
User currently offlineDIA From United States of America, joined Jan 2001, 3273 posts, RR: 27
Posted (10 years 9 months 1 week 5 days 5 hours ago) and read 6448 times:

I came across this pic and the caption got me to thinking. . .just what are some of the lowest outside air temps when flying at altitude (for airliners). I would venture to guess that Concorde recorded the lowest, for an airliner, but what about the no-supersonic a/c?

I've also heard that the lowest "at-altitude" temps occur over the Pacific. . .any truth to that?




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2 replies: All unread, jump to last
 
User currently offlineFredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 1, posted (10 years 9 months 1 week 5 days 4 hours ago) and read 6392 times:

In the standard atmosphere, 216 K or -57 degrees Celsius, between 11,000 FL360) and 25,000 (FL820) meters absolute altitude ASL.

The atmosphere is usually non-standard so you're bound to see lower readings at times, but that's the neighbourhood.

Cheers,
Fred



I thought I was doing good trying to avoid those airport hotels... and look at me now.
User currently offlineB747Skipper From , joined Dec 1969, posts, RR:
Reply 2, posted (10 years 9 months 1 week 5 days 3 hours ago) and read 6346 times:

The coldest OATs that I have encountered were generally around tropical and equatorial areas. It sometimes happens to be at STD - 20 degrees C... I have seen the OAT at some -70 C and was seriously concerned about fuel heat for our tanks... our fuel has to remain above - 37 C... By chance, we do not assume OAT as been the limiting factor, but the RAT (or TAT) which is some 30 degrees warmer than OAT in cruise at Mach 85...
xxx
Since the temperature lapse rate is supposed to stabilize when reaching 36,089 feet, at a value of -56.5 C, the tropopause is much higher in these areas of the globe, the result is that you might be at 41,000 and still below the tropopause...
xxx
Same thing in reverse over polar areas... I have flown a few times at latitudes of 85 N, or straight over the South Pole... it is generally "warmer" over the poles, because the tropopause is often as low as 28,000 feet...
xxx
So a good thing to remember (and a "trick" question) -  Big grin
What is the coldest tropopause...?
Polar tropopause...?
Tropical tropopause...?
xxx
If you think of Polar bears, you are wrong...
The correct answer is that it might be right over... Central Africa...
xxx
Happy contrails -
(s) Skipper
...
Time to go back to the beach and enjoy a cold "Brahma"...


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