Solar Radiation
Author: CislunarSpace
Site: https://cislunarspace.cn
Definition
Solar radiation is electromagnetic wave energy transfer from the sun, representing the primary thermal input source for stratospheric airships. Solar radiation intensity varies with Earth-sun distance, atmospheric transparency, and solar elevation angle, directly affecting the thermal state of airship envelopes and internal helium, thereby influencing buoyancy.
Basic Parameters
Solar Constant
Average solar irradiance outside Earth's atmosphere:
Spectral Distribution
| Band | Wavelength | Energy Ratio | Effect on Airship |
|---|---|---|---|
| UV | <400 nm | ~7% | Envelope aging |
| Visible | 400-700 nm | ~47% | Primary heat source |
| NIR | 700-2500 nm | ~46% | Thermal effect |
Altitude Effects
Radiation at 20 km
| Component | Intensity | Note |
|---|---|---|
| Direct radiation | ~1100 W/m² | Enhanced transmission |
| Diffuse radiation | ~50 W/m² | Thin atmosphere |
| Total radiation | ~1150 W/m² | Higher than ground |
Diurnal Variation
| Period | Radiation Characteristic |
|---|---|
| Noon | Maximum, peak |
| Sunrise/Sunset | Oblique incidence, reduced radiation |
| Night | No solar radiation, relies on daytime heat storage |
Related Concepts
References
- Duffie J A, Beckman W A. Solar Engineering of Thermal Processes[M]. Wiley, 2024.
- NASA. ASTM E-490 Solar Constant[M]. ASTM International, 2023.