Special Terms
Analemma
You can find out where the sun will be directly overhead on any day throughout the year, using an analemma. An analemma is a figure-8 shape that traces where the sun is overhead each day. So, if you went to where the sun was directly overhead every day over the course of a year, and you recorded where you were, the places recorded would eventually create the shape of an analemma after one complete revolution, or one year.
Declination
Declination is the angle between the sun's rays and the Earth's equator.
Direct Sunlight
Direct sunlight is basically where the electromagnetic waves hit the Earth most directly. During the Autumnal equinox, the most direct sunlight is on the equator.
Special Astronomical Dates
These dates are the solstices and equinoxes. On June 21 or 22 is the Summer solstice. On September 22 or 23 is the Autumnal equinox. On December 21 or 22 is the Winter solstice, and the Vernal equinox is on March 21 or 22. Also, the Perihelion (when the Earth is closest to the sun) occurs on January 3 or 4, and the Aphelion (when the Earth is farthest from the sun) occurs on July 3 or 4.
Sunlight/Solar Intensity
On the Earth's surface and atmosphere is where reflection occurs Sunlight is basically the "total frequency spectrum of electromagnetic radiation given off by the sun." Sunlight reaches Earth in about 8.3 minutes. As sunlight travels through the atmosphere, some is absorbes by the air and some is reflected back into space. Solar intensity is the strength of the sunlight.
Algorithm for finding solar intensity:
SIN(A) = Intensity; A = angle of the sun's rays
- This algorithim is used for finding the intensity of the sun's rays in a given place. If you know the angle of the sun's rays at a given place, you can use that information to find out the strength of the sunlight at that place.
Algorithm for finding solar intensity:
SIN(A) = Intensity; A = angle of the sun's rays
- This algorithim is used for finding the intensity of the sun's rays in a given place. If you know the angle of the sun's rays at a given place, you can use that information to find out the strength of the sunlight at that place.
Earth/Sun Changes over the Course of 1 year
Over the year, the Earth revolves around the sun in an ellipse, or oval shape. Since Earth is rotating, it looks like the sun is revolving around the Earth, but it really is not.
Sun's Apparent Path Across the Sky
Each day, shadows are longer at sunset and sunrise, and shortest at noon. During the vernal and autumnal equinoxes, day and night are just about equal in length. Basically, in the summer, the sun's apparent path is longest, and in winter is the shortest. The Earth rotates counterclockwise from the north, which causes the sun to rise in the East and set in the West. The celestial equator is the "projection of Earth's equator onto the sky."
Solar Noon
"The time of solar noon depends on the Equation of Time and on the difference in longitude between your location and the standard meridian of the time zone you are in. It is slightly different for every day of the year."
