Question

Most of us associate 35,000 feet (~10,600 meters) as the height that commercial jets fly. What is the pressure outside of a jet flying at 35,000 feet? How about the temperature outside of that same jet?

Answer 1

The pressure is 24 kPa and the temperature is -54 °C.

Explanation:

Atmospheric pressure

You can calculate the air pressure `p` at a height `h color(white)(l)"m"` above sea level with the formula

`color(blue)(bar(ul(|color(white)(a/a)p/p_0 = ("1 - 2.256 × 10"^"-5"color(white)(l)h)^5.256color(white)(a/a)|)))" "`

where

`"p_0 =` pressure at sea level

Then, at an altitude of 10 600 m,

`p/p_0 = (1 - 2.256 × 10^"-5" × "10 600")^5.256 = (1- 0.239)^5.256 = 0.761^5.256 = 0.24`

Thus, if sea level atmospheric pressure is 100 kPa, the pressure at 10 600 m
is 24 kPa.

(From Engineering ToolBox)

Atmospheric temperature

The atmospheric temperature `T` decreases from sea level temperature `T_0`
by 6.5 °C for every kilometre of height `h`.

Thus, the formula is

`color(blue)(bar(ul(|color(white)(a/a)T = T_0 - 6.5h "°C"color(white)(a/a)|)))" "`

Thus, if sea-level temperature is 15 °C. the temperature at 10 600 m is

`T = "15 °C - 6.5 × 10.6 °C = 15 °C - 68.9 °C = -54 °C"`

(From nc-climate.ncsu.edu)