In article ,
S Green wrote:

"Everett M. Greene" wrote in message
...
Does the lapse rate equation hold in all cases? I was recently
wondering what kind of temperature would be reached at 35 Kft
over Arctic Canada in January. It seemed that the lapse rate
equation would lead you to expect temperatures that would be
causing nitrogen and carbon dioxide to be condensing which
doesn't seem likely.

A few years back, my (then) 4th grade son did his science fair project on how
temperature changes with altitude. Over the course of a year, and
probably a dozen or more family flights, he measured the OAT as a function
of altitude during our climb-outs and descents. He got data from sea level
up to 14,000. Amazingly enough, it averaged out to almost exactly
2 deg C/1000'. He noted that the greatest deviations from that occurred
very close to the ground (within 2000' AGL) and when we were in clouds (IMC).

Now, our Cherokee 6 can't climb up to FL 350, so I have no personal
experience with how high the standard lapse rate holds. However, my son
will tell you that for a clear day, above 2000' AGL, it seems to hold
very very well.

Oh....and he got first place for his science project. I couldn't be a
prouder pilot-papa.

-- Dane