Understanding Summer Solstice Sun Angles
The summer solstice gives the highest noon Sun for many northern sites. It also gives the longest daylight period. This calculator turns that geometry into useful numbers. It uses latitude, solstice type, solar time, object height, surface tilt, and surface direction. The result helps with site planning, garden layout, roof studies, shade checks, and basic astronomy lessons.
Why the Sun Angle Matters
Sun angle controls how high the Sun appears above the horizon. A high angle creates short shadows. A low angle creates long shadows. At solar noon on the June solstice, the Sun is directly above the Tropic of Cancer. On the December solstice, it is above the Tropic of Capricorn. This difference changes the altitude, zenith angle, daylight length, and shadow ratio for every location.
Planning With the Result
The noon altitude shows the best daily peak. The custom-time altitude shows what happens away from noon. The azimuth tells the compass direction of the Sun. Shadow length uses object height and the tangent of altitude. The daylight estimate uses the sunrise hour angle formula. These outputs are practical for outdoor work, solar sketches, window shade checks, and classroom examples.
Surface and Panel Use
The surface incidence angle compares the Sun ray with a tilted plane. A smaller incidence angle means the Sun is closer to perpendicular to that surface. This is useful for simple solar panel studies. It also helps compare wall, roof, and ground exposure. The calculator does not replace local weather data, horizon obstructions, or professional solar design. It gives a clean mathematical estimate from standard spherical geometry.
Accuracy Notes
Use signed latitude carefully. North is positive. South is negative. Local solar time is different from clock time when longitude and time zone effects are ignored. For fast planning, solar noon is 12. For detailed field work, adjust for longitude, time zone, and the equation of time. The solstice declination is rounded to 23.44 degrees, which is accurate enough for most educational and early planning needs. Always review nearby trees, buildings, hills, and seasonal access paths before choosing a final design. Real sites rarely have a perfectly open horizon line.