1. What is the Length of Day Equation?

The Length of Day equation calculates the duration of daylight hours at a given latitude and solar declination. It's based on astronomical calculations of the sun's position relative to Earth.

2. How Does the Calculator Work?

The calculator uses the Length of Day equation:

Where:

• \( DL \) — Length of day (hours)
• \( \phi \) — Latitude (degrees)
• \( \delta \) — Solar declination (degrees)

Explanation: The equation calculates the time between sunrise and sunset based on the Earth's tilt and the observer's latitude.

3. Importance of Day Length Calculation

Details: Day length affects agriculture, solar energy production, biological rhythms, and seasonal activities. It's crucial for astronomical observations and climate studies.

4. Using the Calculator

Tips: Enter latitude between -90° (South Pole) and +90° (North Pole). Declination ranges from -23.45° to +23.45° (Earth's axial tilt). Both values must be in degrees.

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 seasonally due to Earth's tilt.

Q2: How does latitude affect day length?
A: Day length variation increases with latitude. Near the poles, days can be 24 hours (midnight sun) or 0 hours (polar night) during solstices.

Q3: What's the day length at the equator?
A: Approximately 12 hours year-round, with small variations due to atmospheric refraction and the sun's angular size.

Q4: How accurate is this calculation?
A: It provides theoretical daylight duration. Actual sunrise/sunset times may differ slightly due to atmospheric refraction and local topography.

Q5: What are typical declination values?
A: +23.45° at June solstice, -23.45° at December solstice, and 0° at equinoxes.