Lapse Rate Model
Computation of atmospheric parameters through the temperature gradient.
Description
The Lapse Rate Model block implements formulas to calculate the parameters of a standard atmosphere: temperature, sound speed, pressure and air density.
Formulas for calculating troposphere parameters:
Formulas for calculating the tropopause parameters (beginning of the stratosphere):
Where:
-
- temperature at mean sea level, K;
-
- air density at mean sea level, kg/m³;
-
- pressure at mean sea level, Pa;
-
- geopotential height, m;
-
- troposphere height, m
-
- temperature at altitude , K
-
- air density at altitude , kg/m3;
-
- pressure at altitude , Pa
-
- sound speed at height , m/s;
-
- temperature gradient over geopotential height, K/m;
-
- specific gas constant, J/kg⋅K;
-
- adiabatic index;
-
- free fall acceleration, m/s2.
The Lapse Rate Model block works in SI units.
Limitations
-
Below a height of 0 m and above the tropopause height, temperature and pressure values remain unchanged.
-
The density and speed of sound are calculated using the ideal gas equation.
Ports
Output
T (K) - temperature
scalar
| vector
Temperature, K.
Data types: Float64
.
a (m/s) - speed of sound
scalar
| vector
Speed of sound, m/s.
Data types: Float64
.
P (Pa) - pressure
scalar
| vector
Pressure, Pa.
Data types: Float64
.
ρ (kg/m3) - air density
scalar
| vector
Density of air, kg/m³.
Data types: Float64
.
Parameters
Acceleration due to gravity (m/s^2) - free fall acceleration
9.80665 (by default)
| scalar
Free-fall acceleration, m/s2. By default, the value of free fall acceleration at mean sea level is used.
Ratio of specific heats - adiabatic index
1.4 (By default)
| scalar
.
Adiabatic index.
Characteristic gas constant (J/Kg/K) - specific gas constant
287.0531 (By default)
| scalar
Specific gas constant, J/kg⋅K.
Lapse rate (K/m) - temperature gradient
0.0065 (By default)
| scalar
Temperature gradient along geopotential height, K/m.
Height of troposphere (m) - height of troposphere
11000.0 (By default)
| scalar
Height of troposphere, m.
Height of tropopause (m) - height of tropopause
20000.0 (By default)
| scalar
Height of tropopause, m.
Air density at mean sea level (Kg/m^3) - air density at mean sea level
1.225 (By default)
| scalar
Air density at mean sea level, kg/m3.
Ambient pressure at mean sea level (N/m^2) - pressure at mean sea level
101325.0 (By default)
| scalar
Pressure at mean sea level, N/m2 (Pa).
Ambient temperature at mean sea level (K) - temperature at mean sea level
288.15 (By default)
| scalar
.
Ambient temperature at mean sea level, K.
Lowest altitude (m) - lowest layer height
0.0 (By default)
| scalar
The height corresponding to the beginning of the layer, m. The value must be less than the height of the tropopause.