Table of Contents
Advertisement
INSTALLATION
3.2.4 Installation for measurement of diffuse radiation
For measuring sky radiation, the direct solar radiation is best intercepted by a
small disk or sphere. The shadow of
the disk must cover the pyranometer
domes completely. However, to
follow the sun's apparent motion, a
power-driven tracking device is
necessary.
This can be done with the 2AP
tracker, designed to track the sun
under all weather conditions. More
information about the combination of
CM 11 and tracker is given in the
2AP tracker manual.
Figure 12 2AP tracker with pyranometer
Alternatively the use of a shadow ring is possible, however less accurate. The
shadow ring intercepts the direct solar radiation some days without
readjustment, but also a proportion of the diffuse sky radiation. Therefore
corrections for this to the recorded data are necessary.
Kipp & Zonen supplies a universal shadow ring CM 121 for all latitudes. In the
CM 121 manual, installation instructions and correction factors are given.
3.2.5 Installation for measurement of albedo
The lower sensor of the albedometer construction, the pyranometer in the
inverted position, measures the reflected solar radiation.
According to the WMO the height should be 1-2 meters above a surface
covered by short cut grass.
The mounting device should not interfere too much with the field of view of the
instrument. A construction as in figure 13 is suitable.
27
Advertisement
Table of Contents
