Once you know latitude, the other piece of information necessary for plotting
where shade will fall is the direction of north at your site. Plans and maps often
have an arrow indicating the general direction of north but it is essential that this
information be accurate and that True North be used for plotting shade.
is the direction of north when magnetic variance is corrected.
Magnetic variation differs significantly, according to location. It can be determined
by consulting a surveyor or referring to navigational charts. The bearing (azimuth
angle) of the sun at solar noon is always true north, expressed as 0 degrees.
Other types of ‘north’ are:
- Magnetic North is the direction of north as indicated by compass
readings; it cannot be used for shadow projection.
- Grid North appears on geographic information systems (GIS)
maps which are increasingly being used by local governments and is very close
to true north.
will assist you to easily and accurately find
True North by guiding you to resources in your location. Most of them are websites
for mapping authorities or local councils where you can buy a plan for your site showing
True North. WebShade has tested these resources to check reliability and delivery