IdealGasLaw
Ideal gas law for atmospheric air density: rho = M_air * p / (R * T). Migrated from AtmosphericDynamics.jl@816cc391 src/seinfeld_pandis_ch1.jl:68 (`IdealGasLaw` @component). Implements Seinfeld & Pandis Ch 1 Eq 1.2. Parameterized as observed-only: T and p are inputs (parameters in standalone form), rho is the algebraic output. Upstream the Julia @component declares T and p as @variables for composition into a parent system; for standalone serialization (3 unknowns vs 1 equation otherwise), they are declared as parameters here, mirroring the WaterEquilibrium serialization pattern.
Description
Ideal gas law for atmospheric air density: rho = M_air * p / (R * T). Migrated from AtmosphericDynamics.jl@816cc391 src/seinfeld_pandis_ch1.jl:68 (IdealGasLaw @component). Implements Seinfeld & Pandis Ch 1 Eq 1.2. Parameterized as observed-only: T and p are inputs (parameters in standalone form), rho is the algebraic output. Upstream the Julia @component declares T and p as @variables for composition into a parent system; for standalone serialization (3 unknowns vs 1 equation otherwise), they are declared as parameters here, mirroring the WaterEquilibrium serialization pattern.
Reference
_source_ref: AtmosphericDynamics.jl@816cc391:src/seinfeld_pandis_ch1.jl:68
Upstream IdealGasLaw is an MTK @component where T and p are @variables driven by a parent system. For standalone serialization (and to make the component well-posed in isolation), T and p are declared as parameters here — matching the (S, observed-only) classification in docs/migration-tracker.md. Constant values R = 8.314 J/(mol*K) and M_air = 0.02897 kg/mol come from the upstream module’s R_GAS and M_AIR (Seinfeld & Pandis Appendix A).
Tolerance rationale (model-level rel=1e-6): observed-only single-equation algebraic system (no ODE integration); 1e-6 covers float64 roundoff in the M_air * p / (R * T) closed-form expression across the atmospheric T range (216–313 K) and p range (22.6–110 kPa)._
Parameters
| Name | Units | Default | Description |
|---|---|---|---|
T | K | 298.15 | Temperature |
p | Pa | 101325.0 | Atmospheric pressure |
R | J/mol/K | 8.314 | Universal gas constant (Seinfeld & Pandis Appendix A) |
M_air | kg/mol | 0.02897 | Molecular weight of dry air (Seinfeld & Pandis Appendix A; 28.97 g/mol) |
Observed
| Name | Units | Default | Description |
|---|---|---|---|
rho | kg/m^3 | Air density |
Observed expressions
$$ rho = \frac{M_{air} \cdot p}{R \cdot T} $$Air density
Analyses
rho_vs_temperature_at_sea_level_pressure
Air density as a function of temperature at sea-level pressure (p = 101325 Pa). Reproduces the canonical inverse-temperature curve of Seinfeld & Pandis Eq 1.2 across the atmospheric range (216–313 K).
Time span: 0.0 → 1.0
Swept over: T
rho_vs_pressure_at_standard_T
Air density as a function of pressure at standard sea-level temperature (T = 288.15 K). Verifies linear scaling rho ∝ p across the tropospheric pressure range (22.6–110 kPa).
Time span: 0.0 → 1.0
Swept over: p
coupled_T_and_p_sweep
Two-dimensional sweep over T (cold tropopause to hot surface) and p (tropopause to above-sea-level). Surfaces the joint dependence of rho on temperature and pressure.
Time span: 0.0 → 1.0
Swept over: T, p
Raw .esm
Raw .esm JSON (this component)
{
"reference": {
"notes": "source_ref: AtmosphericDynamics.jl@816cc391:src/seinfeld_pandis_ch1.jl:68\nUpstream `IdealGasLaw` is an MTK `@component` where T and p are `@variables` driven by a parent system. For standalone serialization (and to make the component well-posed in isolation), T and p are declared as parameters here — matching the (S, observed-only) classification in docs/migration-tracker.md. Constant values R = 8.314 J/(mol*K) and M_air = 0.02897 kg/mol come from the upstream module's `R_GAS` and `M_AIR` (Seinfeld & Pandis Appendix A).\n\nTolerance rationale (model-level rel=1e-6): observed-only single-equation algebraic system (no ODE integration); 1e-6 covers float64 roundoff in the M_air * p / (R * T) closed-form expression across the atmospheric T range (216–313 K) and p range (22.6–110 kPa)."
},
"tolerance": {
"rel": 1e-06
},
"variables": {
"T": {
"type": "parameter",
"units": "K",
"default": 298.15,
"description": "Temperature"
},
"p": {
"type": "parameter",
"units": "Pa",
"default": 101325.0,
"description": "Atmospheric pressure"
},
"R": {
"type": "parameter",
"units": "J/mol/K",
"default": 8.314,
"description": "Universal gas constant (Seinfeld & Pandis Appendix A)"
},
"M_air": {
"type": "parameter",
"units": "kg/mol",
"default": 0.02897,
"description": "Molecular weight of dry air (Seinfeld & Pandis Appendix A; 28.97 g/mol)"
},
"rho": {
"type": "unknown",
"units": "kg/m^3",
"description": "Air density"
}
},
"equations": [
{
"lhs": "rho",
"rhs": {
"op": "/",
"args": [
{
"op": "*",
"args": [
"M_air",
"p"
]
},
{
"op": "*",
"args": [
"R",
"T"
]
}
]
}
}
],
"tests": [
{
"id": "std_sea_level",
"description": "U.S. Standard Atmosphere sea-level reference: T=288.15 K, p=101325 Pa. Canonical air density rho ≈ 1.225 kg/m^3 (Seinfeld & Pandis Ch 1).",
"parameter_overrides": {
"T": 288.15,
"p": 101325.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"assertions": [
{
"variable": "rho",
"time": 0.0,
"expected": 1.2252831566631774
}
]
},
{
"id": "zero_celsius",
"description": "Standard pressure at the freezing point of water: T=273.15 K, p=101325 Pa. Cold-surface reference.",
"parameter_overrides": {
"T": 273.15,
"p": 101325.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"assertions": [
{
"variable": "rho",
"time": 0.0,
"expected": 1.2925694365458342
}
]
},
{
"id": "std_25C",
"description": "Standard laboratory conditions: T=298.15 K (25°C), p=101325 Pa.",
"parameter_overrides": {
"T": 298.15,
"p": 101325.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"assertions": [
{
"variable": "rho",
"time": 0.0,
"expected": 1.1841869582173221
}
]
},
{
"id": "tropopause_11km",
"description": "U.S. Standard Atmosphere tropopause (~11 km): T=216.65 K, p=22632 Pa. Exercises the cold/low-pressure regime.",
"parameter_overrides": {
"T": 216.65,
"p": 22632.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"assertions": [
{
"variable": "rho",
"time": 0.0,
"expected": 0.3640011167935921
}
]
},
{
"id": "hot_surface",
"description": "Hot summertime surface: T=313.15 K (40°C), p=101325 Pa.",
"parameter_overrides": {
"T": 313.15,
"p": 101325.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"assertions": [
{
"variable": "rho",
"time": 0.0,
"expected": 1.1274639680424545
}
]
},
{
"id": "cold_surface",
"description": "Wintertime polar surface: T=253.15 K (-20°C), p=101325 Pa.",
"parameter_overrides": {
"T": 253.15,
"p": 101325.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"assertions": [
{
"variable": "rho",
"time": 0.0,
"expected": 1.394688293867251
}
]
},
{
"id": "mid_troposphere",
"description": "Approximate mid-troposphere (~5 km): T=255.65 K, p=54020 Pa. Joint cold-and-low-pressure case.",
"parameter_overrides": {
"T": 255.65,
"p": 54020.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"assertions": [
{
"variable": "rho",
"time": 0.0,
"expected": 0.7362872123447658
}
]
},
{
"id": "low_pressure",
"description": "Half-pressure case at sea-level temperature: T=288.15 K, p=50000 Pa. Verifies linear scaling of rho with p at fixed T.",
"parameter_overrides": {
"T": 288.15,
"p": 50000.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"assertions": [
{
"variable": "rho",
"time": 0.0,
"expected": 0.6046302278130656
}
]
},
{
"id": "high_pressure",
"description": "Above-standard pressure case at sea-level temperature: T=288.15 K, p=110000 Pa.",
"parameter_overrides": {
"T": 288.15,
"p": 110000.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"assertions": [
{
"variable": "rho",
"time": 0.0,
"expected": 1.3301865011887444
}
]
}
],
"analyses": [
{
"id": "rho_vs_temperature_at_sea_level_pressure",
"description": "Air density as a function of temperature at sea-level pressure (p = 101325 Pa). Reproduces the canonical inverse-temperature curve of Seinfeld & Pandis Eq 1.2 across the atmospheric range (216–313 K).",
"initial_state": {},
"parameters": {
"p": 101325.0
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"parameter_sweep": {
"type": "cartesian",
"dimensions": [
{
"parameter": "T",
"range": {
"start": 216.65,
"stop": 313.15,
"count": 25,
"scale": "linear"
}
}
]
},
"plots": [
{
"id": "rho_vs_T",
"type": "line",
"description": "Air density rho as a function of temperature at p = 101325 Pa.",
"x": {
"variable": "T",
"label": "Temperature (K)"
},
"y": {
"variable": "rho",
"label": "Air density (kg/m^3)"
}
}
]
},
{
"id": "rho_vs_pressure_at_standard_T",
"description": "Air density as a function of pressure at standard sea-level temperature (T = 288.15 K). Verifies linear scaling rho ∝ p across the tropospheric pressure range (22.6–110 kPa).",
"initial_state": {},
"parameters": {
"T": 288.15
},
"time_span": {
"start": 0.0,
"end": 1.0
},
"parameter_sweep": {
"type": "cartesian",
"dimensions": [
{
"parameter": "p",
"range": {
"start": 22632.0,
"stop": 110000.0,
"count": 20,
"scale": "linear"
}
}
]
},
"plots": [
{
"id": "rho_vs_p",
"type": "line",
"description": "Air density rho as a function of pressure at T = 288.15 K.",
"x": {
"variable": "p",
"label": "Pressure (Pa)"
},
"y": {
"variable": "rho",
"label": "Air density (kg/m^3)"
}
}
]
},
{
"id": "coupled_T_and_p_sweep",
"description": "Two-dimensional sweep over T (cold tropopause to hot surface) and p (tropopause to above-sea-level). Surfaces the joint dependence of rho on temperature and pressure.",
"initial_state": {},
"parameters": {},
"time_span": {
"start": 0.0,
"end": 1.0
},
"parameter_sweep": {
"type": "cartesian",
"dimensions": [
{
"parameter": "T",
"range": {
"start": 216.65,
"stop": 313.15,
"count": 12,
"scale": "linear"
}
},
{
"parameter": "p",
"range": {
"start": 22632.0,
"stop": 110000.0,
"count": 12,
"scale": "linear"
}
}
]
},
"plots": [
{
"id": "rho_heatmap",
"type": "heatmap",
"description": "Air density rho as a function of T and p.",
"x": {
"variable": "T",
"label": "Temperature (K)"
},
"y": {
"variable": "p",
"label": "Pressure (Pa)"
},
"value": {
"variable": "rho",
"reduce": "final"
}
}
]
}
]
}