Noaa Sunrise Sunset Calculator

NOAA Sunrise/Sunset Equations:

\[ \text{Sunrise} = 12 - \frac{DL}{2} + \text{adjustments} \] \[ DL = \frac{2}{15} \times \arccos(-\tan \phi \tan \delta) \times \frac{180}{\pi} \]

Day Length (DL):

Sunrise:

Sunset:

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1. What is the NOAA Sunrise/Sunset Calculation?

The NOAA (National Oceanic and Atmospheric Administration) sunrise/sunset equations estimate the times of sunrise and sunset based on latitude, solar declination, and timezone. These calculations are essential for astronomy, navigation, and various outdoor activities.

2. How Does the Calculator Work?

The calculator uses the NOAA equations:

\[ \text{Sunrise} = 12 - \frac{DL}{2} + \text{adjustments} \] \[ DL = \frac{2}{15} \times \arccos(-\tan \phi \tan \delta) \times \frac{180}{\pi} \]

Where:

\( DL \) — Day length in hours
\( \phi \) — Latitude in degrees (-90 to 90)
\( \delta \) — Solar declination in degrees (-23.5 to 23.5)
Timezone — Local offset from UTC in hours

Explanation: The equations account for the Earth's axial tilt and the observer's latitude to determine when the sun appears and disappears over the horizon.

3. Importance of Accurate Sunrise/Sunset Times

Details: Precise sunrise/sunset times are crucial for aviation, marine navigation, photography, religious observances, and solar energy planning.

4. Using the Calculator

Tips: Enter latitude (-90 to 90), solar declination (-23.5 to 23.5), and your local timezone offset from UTC. For best results, use accurate solar declination values for your date.

5. Frequently Asked Questions (FAQ)

Q1: What is solar declination?
A: Solar declination is the angle between the rays of the Sun and the plane of the Earth's equator, varying between ±23.5° throughout the year.

Q2: Why does day length vary?
A: Day length varies due to Earth's axial tilt (23.5°) and its orbit around the Sun, causing seasonal changes in sunlight duration.

Q3: How accurate are these calculations?
A: The calculations are typically accurate to within a minute for most locations, though local topography and atmospheric conditions can affect actual times.

Q4: What about daylight saving time?
A: The calculator uses the timezone offset you provide. Add 1 hour to your standard timezone if daylight saving is in effect.

Q5: How do I find solar declination for a specific date?
A: Solar declination can be calculated or found in astronomical tables. It's approximately +23.5° at June solstice and -23.5° at December solstice.