Enter Sun Altitude Details
Example Data Table
The following examples show typical inputs and expected solar altitude behavior.
| Location | Date | Local Time | Latitude | Longitude | Time Zone | Expected Result |
|---|---|---|---|---|---|---|
| New York | 2026-06-21 | 12:00 | 40.7128 | -74.0060 | -5 | High summer solar altitude |
| London | 2026-12-21 | 12:00 | 51.5074 | -0.1278 | 0 | Low winter solar altitude |
| Karachi | 2026-03-20 | 12:00 | 24.8607 | 67.0011 | 5 | Strong midday sun angle |
Formula Used
The calculator estimates the sun altitude with standard solar geometry.
Day angle:
B = 360 / 365 × (N - 81)
Equation of time:
EoT = 9.87 sin(2B) - 7.53 cos(B) - 1.5 sin(B)
Time correction:
TC = 4 × (Longitude - Standard Meridian) + EoT
Solar time:
Solar Time = Local Time + TC / 60
Solar declination:
δ = 23.45 × sin[360 / 365 × (N - 81)]
Hour angle:
H = 15 × (Solar Time - 12)
Solar altitude:
sin(α) = sin(φ)sin(δ) + cos(φ)cos(δ)cos(H)
Here, α is solar altitude, φ is latitude, δ is declination, and H is hour angle.
How to Use This Calculator
- Enter the latitude of the observation point.
- Enter longitude using positive east and negative west values.
- Add the local time zone offset from UTC.
- Select the date of the observation.
- Enter the local hour, minute, and second.
- Add observer height if horizon dip matters.
- Adjust pressure and temperature for refraction correction.
- Press the calculate button to view the result.
- Download the result as CSV or PDF when needed.
Understanding Solar Altitude
What Solar Altitude Means
Solar altitude is the angle between the sun and the local horizon. A value of zero degrees means the sun is on the horizon. A positive value means the sun is above the horizon. A negative value means the sun is below it. This angle changes during the day. It also changes with season and location.
Why the Angle Matters
Solar altitude helps many practical plans. Architects use it for shade studies. Farmers use it for crop exposure. Photographers use it for lighting direction. Solar designers use it for panel placement. Outdoor workers use it for heat planning. The angle affects shadows, glare, and daylight strength.
Location and Time Inputs
Latitude controls the north or south position. Longitude helps correct clock time into solar time. The time zone sets the standard meridian. The date gives the seasonal position of the sun. Small errors in time can shift the result. This is important near sunrise and sunset.
Advanced Corrections
This calculator includes useful advanced corrections. The equation of time adjusts clock time. Atmospheric refraction lifts the apparent sun near the horizon. Observer height adjusts the visible horizon. Air mass estimates the path length through the atmosphere. These values improve field planning. They also help compare different observation sites.
Reading the Result
True altitude is the geometric sun angle. Apparent altitude includes refraction. Visible altitude also considers observer height. Zenith angle is measured from straight overhead. Azimuth shows compass direction. Air mass grows when the sun is low. Use all results together for better decisions.
FAQs
1. What is the altitude of the sun?
It is the angle between the sun and the horizon. A higher value means the sun is higher in the sky.
2. What does negative solar altitude mean?
Negative altitude means the sun is below the horizon. This usually happens before sunrise or after sunset.
3. Why does longitude affect the result?
Longitude changes the difference between clock time and solar time. This affects the calculated hour angle.
4. What is solar azimuth?
Solar azimuth is the compass direction of the sun. It is measured around the horizon from north.
5. What is the zenith angle?
The zenith angle is measured from directly overhead. It equals ninety degrees minus the solar altitude.
6. Why include atmospheric refraction?
Refraction bends sunlight near the horizon. It makes the sun appear slightly higher than its geometric position.
7. Can this calculator help solar panel planning?
Yes. It helps estimate sun height and direction. Use it with local shading and panel tilt checks.
8. Is daylight saving time supported?
Yes. Use the daylight saving checkbox when your entered clock time includes a daylight saving adjustment.