Total air temperature

In aviation, stagnation temperature is known as total air temperature and is measured by a temperature probe mounted on the surface of the aircraft. The probe is designed to bring the air to rest relative to the aircraft. As the air is brought to rest, kinetic energy is converted to internal energy. The air is compressed and experiences an adiabatic increase in temperature. Therefore total air temperature is higher than the static (or ambient) air temperature.

Total air temperature is an essential input to an air data computer in order to enable computation of static air temperature and hence true airspeed.

The relationship between static and total air temperatures is given by:

where:

${\displaystyle T_{s}=}$ static air temperature, SAT (kelvins or degrees Rankine)
${\displaystyle T_{\mathrm {total} }=}$ total air temperature, TAT (kelvins or degrees Rankine)
${\displaystyle M_{a}=}$ Mach number
${\displaystyle \gamma \ =\,}$ ratio of specific heats, approx 1.400 for dry air

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