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NOAA Sunrise/Sunset Algorithm:
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The NOAA (National Oceanic and Atmospheric Administration) sunrise/sunset algorithm calculates the times of sunrise, sunset, solar noon, and day length for any location on Earth and any date. It accounts for atmospheric refraction and the observer's elevation.
The calculator uses the NOAA algorithm:
Where:
Explanation: The algorithm calculates the Sun's position accounting for Earth's elliptical orbit and axial tilt, then determines when the Sun's upper limb appears or disappears at the horizon.
Details: Accurate sunrise/sunset times are crucial for astronomy, photography, agriculture, religious observances, and various outdoor activities. They also help in designing solar energy systems.
Tips: Enter latitude (-90 to 90), longitude (-180 to 180), and date. Positive values are North/East, negative are South/West. For best accuracy, use coordinates precise to at least 4 decimal places.
Q1: How accurate is the NOAA algorithm?
A: The algorithm is accurate to within a minute for locations between ±60° latitude, and slightly less accurate near the poles.
Q2: Does it account for elevation?
A: The basic algorithm assumes sea level. Higher elevations may see slightly earlier sunrises and later sunsets.
Q3: What time zone are the results in?
A: Results are in local time for the specified date and location, accounting for time zones and daylight saving time.
Q4: Why are there differences between NOAA and other calculators?
A: Differences may arise from varying definitions of sunrise/sunset, atmospheric models, or rounding methods.
Q5: Can I calculate for past or future dates?
A: Yes, the algorithm works for any date, though very distant dates may have reduced accuracy due to long-term changes in Earth's orbit.