Atmosphere

International Standard Atmosphere (ISA) model and airspeed conversions.

Provides temperature, pressure, density, and speed of sound as functions of geometric altitude, plus conversions between calibrated airspeed (CAS), true airspeed (TAS), and Mach number using compressible flow equations.

Used internally by aircraft speed schedules and wind field pressure-level conversions.

International Standard Atmosphere (ISA) model and airspeed conversions.

Provides the 1976 US Standard Atmosphere (identical to ICAO ISA below 32 km) and compressible-flow airspeed conversions accurate through FL510+.

All public functions accept and return pint.Quantity objects.

temperature_at(altitude)[source]

ISA static temperature at altitude.

Covers the troposphere (lapse rate −6.5 K/km) and the lower stratosphere (isothermal at 216.65 K above 11 km).

Return type:

Quantity

Parameters:

altitude (Quantity)

pressure_at(altitude)[source]

ISA static pressure at altitude.

Return type:

Quantity

Parameters:

altitude (Quantity)

density_at(altitude)[source]

ISA air density at altitude.

Return type:

Quantity

Parameters:

altitude (Quantity)

speed_of_sound(altitude)[source]

Speed of sound at altitude from ISA temperature.

Return type:

Quantity

Parameters:

altitude (Quantity)

cas_to_tas(cas, altitude)[source]

Convert calibrated airspeed to true airspeed at altitude (ISA).

Uses the compressible (isentropic) form, not the incompressible approximation. Accurate for subsonic flight through FL510+.

Return type:

Quantity

Parameters:
tas_to_cas(tas, altitude)[source]

Convert true airspeed to calibrated airspeed at altitude (ISA).

Inverse of cas_to_tas().

Return type:

Quantity

Parameters:
mach_to_tas(mach, altitude)[source]

Convert Mach number to true airspeed at altitude (ISA).

Returns TAS in knots.

Return type:

Quantity

Parameters:
tas_to_mach(tas, altitude)[source]

Convert true airspeed to Mach number at altitude (ISA).

Return type:

float

Parameters: