Standard Sea-Level (SSL) Atmospheric Properties
Reference table for air properties at standard sea-level in SI, metric, and imperial units
SSL Reference Table
| Property | SI Units | Metric Units | Imperial Units |
|---|---|---|---|
| Temperature | 288.15 K | 15 °C | 59 °F |
| Pressure | 101.325 kPa | 1.01325 bar | 14.696 psi |
| Density | 1.225 kg/m³ | 1.225 g/cm³ | 0.0765 lb/ft³ |
| Specific Gas Constant (air) | 287 J/kg·K | 0.287 kJ/kg·K | 171 ft·lbf/lb·°R |
| Gravity | 9.80665 m/s² | 9.807 m/s² | 32.174 ft/s² |
About Standard Sea-Level (SSL) Atmospheric Properties
Standard sea-level (SSL) atmospheric properties define the baseline environmental conditions of the Earth's atmosphere at mean sea level. These reference values—including temperature, pressure, density, gravity, and the specific gas constant—are essential for accurate engineering, thermodynamics, fluid mechanics, HVAC, and aerospace calculations.
SSL conditions provide a consistent baseline for modeling and analysis across multiple disciplines:
- Aerospace Engineering: Calculating lift, drag, and propulsion system performance.
- Thermodynamics & Heat Transfer: Evaluating energy balance, heat exchangers, and HVAC design.
- Fluid Mechanics: Modeling air flow, buoyancy, and compressible fluid behavior.
- Environmental & Meteorology Studies: Standardizing measurements for atmospheric research.
- Mechanical & Structural Engineering: Using gravity and density values for load, stress, and dynamics calculations.
Key SSL Atmospheric Properties
- Temperature: 288.15 K (15 °C / 59 °F). Used as a reference for thermal analysis, energy balance, and atmospheric modeling.
- Pressure: 101.325 kPa (1.01325 bar / 14.696 psi). Serves as a baseline for HVAC design, aircraft performance, and weather data normalization.
- Density: 1.225 kg/m³ (0.001225 g/cm³ / 0.0765 lb/ft³). Key variable in aerodynamics, buoyancy, and fluid mechanics calculations.
- Specific Gas Constant (R): 287 J/kg·K (0.287 kJ/kg·K / 171 ft·lbf/lb·°R). Links pressure, volume, and temperature in the ideal gas law (PV = RT).
- Gravity: 9.80665 m/s² (32.174 ft/s²). Standard gravitational acceleration used in mechanical, structural, and geophysical calculations.
Together, these standard atmospheric properties provide the foundation for accurate and consistent engineering simulations, aerodynamic modeling, thermodynamic calculations, and environmental studies worldwide.