What is Air Mass?
Air mass is a measure of the path length that sunlight travels through Earth's atmosphere. It affects the intensity of sunlight reaching a location. When the sun is directly overhead (zenith), the air mass is at its minimum (AM=1). As the sun's angle decreases, the air mass increases, meaning more atmosphere must be traversed by sunlight.
How to Use This Calculator
- Enter your latitude in degrees. Positive for Northern Hemisphere, negative for Southern Hemisphere.
- Enter the solar altitude angle in degrees. This is the angle above the horizon. You can measure this using a solar transit instrument or find it through astronomical calculations.
- Click the Calculate button.
- The calculator will display the solar declination angle (approximate for the current day), the air mass, and the air mass with k=1 (at sea level).
Significance of Air Mass
Air mass is important in:
- Astronomy: Affects the brightness of stars and planets.
- Meteorology: Influences temperature, humidity, and weather patterns.
- Solar Energy: Determines the efficiency of solar panels based on sunlight intensity.
Important Notes
- This calculator uses a simplified formula for small solar altitude angles. For more precise calculations, especially for high angles, more complex formulas should be used.
- The solar declination angle is approximated for the current day of the year. For historical or future dates, you would need to adjust the day of the year calculation.
- The air mass increases as the sun's angle decreases, meaning sunlight travels through more atmosphere.