Solar Angles
Orbit = Earth orbits around the sun
Axis = Earth rotates on an axis which is at a 23.5 degree tilt from the plane of orbit
Seasons = caused by the changing relationship of the tilted axis to the sun, IE. part of the year the South Pole faces away from the sun and part of the year it is closer.
Declination angle = The tilt of the NOrth Pole in relation to the position of the sun. It tells us about the sun's seasonal relationship to the earth.
Winter solstice = on December 21 the declination is -23.5 deg.
Summer Solstice = on June 21 the declination is +23.5 deg.
Equinoxes = Occurs twice in a year, in spring on March 21 and in fall on September 21, the earths tilt is leaning sideways to the sun, the declination is 0 deg for both.
Determining the sun's position relative to an actual SITE location:
Two angles are required:
altitude (ALT) = angle that describes the height of the sun in the sky. Always measured straight up from the ground.
azimuth (AZ) = angle that describes the compass orientation of the sun, the position either west or east from due south. E.g. sun due south, AZ = 0 deg; sun due east, AZ = 90 deg east of south; sun due west, AZ = 90 deg west of south
Alternate azimuth = due north is 0 degrees and follows a clockwise pattern, east is AZ=90deg, south is AZ=180deg, etc. commonly used in computer programs and architecture
Winter seasonal path = a lot of sun on south facing facades and not much sun elsewhere.
Summer seasonal path = a lot of sun on the east facade, the roof, horizontal skylights and on the west facade.
Maximize glass at south facade allowing heat gain during winter, minimize at east and west facades.
time: 0.75, 4:15-5:00pm 6/14/09
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