Temperature at 45000 ft above sea level?

Answer 1

At 45,000 feet AMSL (Above Mean Sea Level), or '45 angels' as it is know to pilots, the temperature will never be an exact figure for all places and times. What needs to be done is to evalute the altitude, the temperature of the sea surface below, the weather conditions, the atmospheric pressure, and the time of day. Since this is a pleathora of factors, studies are generally done to give a "indication" of what the temperature should be, not an exact temperature of what it must be. Anything short of a static thermometer will result in just a general figure.

With that said, the general answer you are looking for is the result of -

At 45,000' AMSL the air pressure is roughly 2.0 psi (and which would give you about 16% of the oxygen you are used to at sea level). less pressure, less heat. If the sea surface below is between 59 and 72 degrees F, the temperature will likely be:

-70 degrees F.

That's MINUS 70 degrees F.

Bonus info: At -40 degrees F and below, the air is so cold that when breathing in without some warming stage inbetween your lungs and the incoming air, your lungs are likely to be cut to ribbons as the mosture in your lungs is immediately crystalized from the temperture of the air entering them.