Definitions and Help on Terms

H e l p T e r m s:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z View in New Window

Altitude:: The vertical angle between the horizontal and the line connecting to the sun. At sunset/sunrise Altitude is 0 and is 90 degrees when the sun is at the zenith.
Altitude and Azimuth Calculator:: This part of the program calculates the Azimuth and the Altitude of the sun for a day. This could be either for an hour or for the whole day. You will have to calculate some value before you can proceed to the other parts of the program.
Angles:: You could choose between degrees and radians for all the angles.
Archit Jain: Archit Jain is a student of the Master of Building Science Program at the School of Architecture at USC. This program was written as part of his thesis research between January and May 1997.
Azimuth:: The horizontal angle of the sun. This program measures angles from the sun side (South in the Northern Hemisphere and North in the Southern Hemisphere. East is positive and West is negative.

Conversion Tables :: Part of the Help Files. Contain easy to do conversion forms for solar and energy related Metric and British Units.

Declination Angle:: The Angle between the earth-sun line and the equatorial plane. Declination changes with the date and is independent of the location. The declination is maximum (23.45) on the summer/winter solstice and 0 on the equinoxes.
Default Units:: Choose the default units for the form from the option list. For conversion tables look in the help files.
Definitions:: This file
Distance: The units of all distance measures.

Equinox:: The time of the year when the declination of the sun is 0 degrees. On these days, i.e. March 21st and September 21st the days and nights are of equal length.

Generate as Text: Use this option to save your files onto your hard drive. You will have to cut and paste the file as a text document with a ".wrl" extension.
Generate VR:: This is IT! Go on and see your model and how the sun moves around it on the selected day!

HTML:: Hyper Text Markup Language. The language of the World Wide Web, where tags are inserted in text documents which decide the layout of the documents when they are seen in the HTML browsers like Netscape or Internet Explorer.
Hour Angle:: Changes with the time of the day. Changes from 0 to 180 degrees (with 0 at 12 hours), with the morning hours as positive and the afternoon hours as negative.
Hours to Calculate Sun's Animation:: You could choose from the drop down menu, as to which all hours you would like to see the view points from the sun from.
Help Files:: Help files contain the very useful and convenient conversion tables, the resources page and links to other related information on the Internet.

Irregular Site: Enter co-ordinates--clockwise from any point. Center of the site would be at 0,0. X is positive to the right and negative to the left. Y is positive towards you and negative away from you.

Julian Day:: The count of the days of the year starting from 1 on January 1st.

Rectangular Site: Enter length and width.
Resources:: The resources page is your guide to the plug-ins and browser versions that you need to completely use this program. It also has links to other utilities you may need.

Select Date:: Use the drop down menus to select the date for the sun position calculations. In the Hour Menu, there is an "all day" calculation, which would give you calculations for the whole day.
Select Latitude:: Select the latitude of the location. You could select it from the list, or from the world map, by clicking on the world map link, or just entering the exact latitude.
Site Information: Enter details of the site in the following tables. Orientation is clockwise from North.
Summary Annual Values: Check this if you want the summary tables for the entire year for the selected latitude. The values would be for the solstices and the equinox from 6 to 20 hours.
Summer Solstice: The longest day of the year. Declination angle for the Summer Solstice is 23.45 in the Northern Hemisphere and it occurs on the 21st of June. In the Southern Hemisphere, the summer solstice occurs on December 21, and the declination angle is -23.45 degrees.
Sunrise and Sunset Times and Azimuths: Use this form to calculate the sunrise and the sunset times for a location and the azimuth at which the sun rises and sets.
Surrounding Buildings and Locations: Enter the dimensions of the surrounding buildings and their locations. X is positive to the right and negative to the left. Y is positive towards you and negative away from you. Orientation is clockwise from North. Color helps identify the building in the VRML scene.

Trees and Locations:: Select trees from the drop down menus and enter location coordinates. X is positive to the right and negative to the left. Y is positive towards you and negative away from you.

VRML: Virtual Reality Modeling Language, initially expanded as the Virtual Reality Markup Language, (like HTML) but changed due to extended scope. This program uses VRML 2.0 specifications which were released in August 1996.
View Points and Animation:: You could define a custom viewpoint. The description would appear in the VRML browser. An orientation of 0 looks directly North. (South in the Southern Hemisphere)
Virtual Reality Builder:: This form takes in the users' inputs and generates the Virtual Reality file written in the Virtual Reality Modeling Language (VRML), which is seen by the VRML browser. Options include single value plot, multiple value plots and animation of sun path.

Web Indices:: Links to other resources on similar topics on the Web.
Winter Solstice: The shortest day of the year. Declination angle for the Winter Solstice is -23.45 in the Northern Hemisphere and it occurs on the 21st of December. In the Southern Hemisphere, the winter solstice occurs on June 21, and the declination angle is 23.45 degrees.

Copyright © Archit Jain, USC School of Architecture, 1997. All Rights Reserved.

This page is part of the Online Solar Position Calculator and VRML Builder--VRSolar. If you have reached here directly from the Web, please go to the Start Page.