How do you explain outside temp - free fall?

Question

On the remarkable Free Fall recently televised, the outside temperature dropped to minus 92 degrees F during the ascent. Then as the capsule neared the final jump altitude, the outside temp had warmed up to about minus 15, or minus 20 degrees F. How is it possible for the temperature to warm up as you go closer and closer to a true vacuum?

Michel Verheughe · Accepted Answer

First of all, the temperature sinks with altitude in the troposphere because as warm air rises, it cools down by adiabatic effect. Colder air is denser and therefore heavier and it sinks too, mostly at night. But the convection of warm air is stronger and the temperature falls about 0.65 C per 100 meters.

Once in the stratosphere, the temperature rises with altitude because here, the sun meet the molecules of ozone. This cause an inversion: warm air above cold one and nothing rises. This is why there are no clouds in the stratosphere.

And this is why, as the Red Bull Stratos went into the stratosphere (I think it went 39 km high, isn't it?) the temperature started increasing. Note that the stratosphere is higher over the equator than the poles, perhaps 18 km high and only 10 km over the poles. It also mean that the tropopause, the top of the troposphere is much colder over the equator! Perhaps as cold as -80 C vs. -40 over the poles. This is due to the fact that equatorial cyclones lift the air upwards and so does the centrifugal force of the earth's rotation.

How do you explain outside temp - free fall?

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