A spherical sundial with hour markings and a movable gnomon at Green's Windmill, Nottingham.

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Preparing the 3D view

Preparing lighting and the first complete frame…

Model scale

Local sky sphere. horizon and solar path use true angles.

2026-05-27 · latitude 51.5° · daylight 15.91 h at a geometric horizon. Selected local solar time 12.0 h; altitude 59.8°. The gnomon shadow follows the Sun and ends at the displayed ground edge. Refraction is excluded.

Solar altitude and sun path

Compare the Sun’s daily path at different latitudes and explain how the season changes noon altitude and day length.

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Why it happens

Solar altitude is the Sun’s angle above the horizon. It changes through the day and year, while latitude determines how high the Sun can climb and whether it rises or sets at all.

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A working sundial at Green's Windmill, Nottingham. A gnomon's shadow connects the Sun's apparent direction with local solar time.

Try a comparison

Change Latitude and Date, then compare the highest solar altitude and length of daylight. Look for a date and latitude with no sunset.

Reading the result

The model shows geometric solar directions; local terrain and atmospheric refraction can change an observed sunrise or sunset.

A common misunderstanding

The Sun is directly overhead at local noon everywhere on Earth.

Local solar noon is when the Sun reaches its daily highest position, but that position need not be overhead. Noon altitude depends on latitude and solar declination. The Sun can be directly overhead only between the tropics, and only on dates appropriate to the latitude.

Cases

Exam language

Solar altitude

The angle of the Sun above the observer’s horizon. A higher Sun concentrates a beam over a smaller horizontal area and shortens a vertical object’s shadow. Altitude depends on latitude, date and time of day.

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A working sundial at Green's Windmill, Nottingham. A gnomon's shadow connects the Sun's apparent direction with local solar time.

Sun path

The apparent arc followed by the Sun across the sky during a day. Its height, direction and duration above the horizon depend on latitude and date. Comparing paths explains seasonal changes in daylight and in the length of shadows.

Declination

The angular position of the Sun north or south of the celestial equator, equivalent to the latitude of the subsolar point. It varies between about 23.44° north and south through the year and helps determine noon altitude and daylight duration.

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Meteosat-9 observed this day–night boundary on 21 December 2010. Earth's tilted axis puts the subsolar point south of the equator and gives southern latitudes longer days. Declination is the Sun's angle north or south of the equatorial plane; the tilt of the boundary is observational evidence, not an angle scale.

Noon altitude

The Sun’s angle above the horizon at local solar noon. In a simple geometric calculation it is 90° minus the absolute difference between latitude and solar declination. A negative value means the Sun remains below the horizon at noon.

Day length

The time between sunrise and sunset at a place. It varies mainly with latitude and the time of year because Earth has a tilted axis. Day length differs from the approximately 24-hour solar day, which includes darkness.

Gnomon

The part of a sundial that casts a shadow. For a vertical gnomon on level ground, shadow length depends on its height and the Sun's altitude.

Tropics

The region between the Tropic of Cancer and Tropic of Capricorn, approximately 23.44 degrees north and south. The Sun can be directly overhead only within this belt, on dates determined by latitude. Tropical climates still vary greatly in rainfall and elevation.

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NASA Blue Marble monthly composite in an equirectangular latitude–longitude grid. Latitude measures angular distance north or south of the equator; parallels run east–west. The geographic reference lines are mathematical, not marks on the land.

Latitude

The angular position of a place north or south of the equator, expressed in degrees. Latitude helps determine solar altitude and seasonal day length. Lines of equal latitude are parallels, unlike meridians, which measure longitude.

Year0.40Latitude51.5°Local solar time12.00 h