1. What is the Daylight Calculation?

The daylight calculation estimates the length of daylight (sunrise to sunset) at a given latitude on a specific date (represented by solar declination). It's based on astronomical formulas that account for Earth's axial tilt and position in its orbit.

2. How Does the Calculator Work?

The calculator uses the daylight formula:

Where:

• \( DL \) — Daylight length in hours
• \( \phi \) — Latitude in degrees (-90 to 90)
• \( \delta \) — Solar declination in degrees (-23.5 to 23.5)

Explanation: The formula calculates the hour angle of sunrise/sunset and converts it to time. The factor of 2 accounts for both sunrise and sunset angles, and the division by 15 converts degrees to hours (since Earth rotates 15° per hour).

3. Importance of Daylight Calculation

Details: Knowing daylight duration is crucial for agriculture, solar energy planning, architectural design, and understanding seasonal variations in different geographic locations.

4. Using the Calculator

Tips: Enter latitude between -90° (South Pole) and 90° (North Pole). Declination ranges from -23.5° (winter solstice) to +23.5° (summer solstice), with 0° at equinoxes.

5. Frequently Asked Questions (FAQ)

Q1: What is solar declination?
A: Solar declination is the angle between the Sun's rays and Earth's equatorial plane, varying between ±23.5° throughout the year due to Earth's axial tilt.

Q2: How accurate is this calculation?
A: It provides theoretical maximum daylight, not accounting for atmospheric refraction, terrain, or twilight periods which can add several minutes of daylight.

Q3: What's the daylight at the poles?
A: At summer solstice (δ ≈ 23.5°), polar day occurs with 24 hours of daylight. At winter solstice (δ ≈ -23.5°), polar night occurs with 0 hours of daylight.

Q4: How does latitude affect daylight?
A: Daylight variation increases with latitude. Near the equator, daylight is nearly constant (~12 hours). At higher latitudes, seasonal variation becomes extreme.

Q5: Can I calculate sunset/sunrise times with this?
A: This gives total daylight duration. For actual sunrise/sunset times, you'd need to calculate the hour angle and adjust for longitude and time zone.