1. What is a Daylight Hours Calculator?

Definition: This calculator estimates the number of daylight hours based on latitude and solar declination angle.

Purpose: It helps astronomers, gardeners, and outdoor planners determine the length of daylight at specific locations and dates.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• Hours — Duration of daylight (hours)
• φ (phi) — Latitude of the location (degrees)
• δ (delta) — Solar declination angle (degrees)

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

3. Importance of Daylight Hours Calculation

Details: Knowing daylight duration helps in agriculture, solar energy planning, construction scheduling, and understanding seasonal changes.

4. Using the Calculator

Tips: Enter the latitude (-90 to 90 degrees) and solar declination angle (-23.45 to 23.45 degrees). The calculator handles the trigonometric calculations.

5. Frequently Asked Questions (FAQ)

Q1: What is solar declination angle?
A: The angle between the Sun's rays and the Earth's equatorial plane, varying between ±23.45° throughout the year.

Q2: How do I find the declination for a specific date?
A: Use our Solar Declination Calculator or astronomical tables. It's approximately δ ≈ 23.45° × sin(360° × (284 + n)/365).

Q3: Why does the formula use arccos?
A: The arccosine function calculates the hour angle when the Sun is at the horizon, determining sunrise/sunset times.

Q4: What about polar day/night?
A: The calculator automatically handles extreme cases (24h daylight or 0h daylight) when the arccos argument is outside [-1,1].

Q5: Does this account for atmospheric refraction?
A: No, this gives theoretical daylight. Actual daylight is slightly longer due to atmospheric effects bending sunlight.