Sun chart
Encyclopedia
A Sun chart is a graph of the ecliptic
of the Sun through the sky throughout the year at a particular latitude
.
Most sun charts plot azimuth versus altitude throughout the days of the winter solstice
and summer solstice
, as well as a number of intervening days. Since the movement of the Sun is symmetrical about the solstice, it is only necessary to plot dates for one half of the year.
The graph may show the entire horizon or only that half of the horizon closest to the equator
. Sky view obstructions can be superimposed upon a Sun chart to obtain the insolation
of a location.
Ecliptic
The ecliptic is the plane of the earth's orbit around the sun. In more accurate terms, it is the intersection of the celestial sphere with the ecliptic plane, which is the geometric plane containing the mean orbit of the Earth around the Sun...
of the Sun through the sky throughout the year at a particular latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
.
Most sun charts plot azimuth versus altitude throughout the days of the winter solstice
Winter solstice
Winter solstice may refer to:* Winter solstice, astronomical event* Winter Solstice , former band* Winter Solstice: North , seasonal songs* Winter Solstice , 2005 American film...
and summer solstice
Summer solstice
The summer solstice occurs exactly when the axial tilt of a planet's semi-axis in a given hemisphere is most inclined towards the star that it orbits. Earth's maximum axial tilt to our star, the Sun, during a solstice is 23° 26'. Though the summer solstice is an instant in time, the term is also...
, as well as a number of intervening days. Since the movement of the Sun is symmetrical about the solstice, it is only necessary to plot dates for one half of the year.
The graph may show the entire horizon or only that half of the horizon closest to the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
. Sky view obstructions can be superimposed upon a Sun chart to obtain the insolation
Insolation
Insolation is a measure of solar radiation energy received on a given surface area in a given time. It is commonly expressed as average irradiance in watts per square meter or kilowatt-hours per square meter per day...
of a location.