Environmental Engineering Reference
In-Depth Information
Figure 2.4
Sun Height at Solar Noon and Air Mass (AM) Values for Various
Dates in Berlin (top) and Cairo (bottom)
and weather are important as well. The daily irradiation in central Europe can
reach values above 7.5 kWh/(m
2
day) in summer, whereas single days in winter
can have less than 0.1 kWh/(m
2
day). Figure 2.5 shows the variation in the
irradiance for a cloudless day in summer (2 July) and in winter (28 December)
as well as a very cloudy day in winter (22 December) for Karlsruhe in southern
Germany.
The annual irradiation varies significantly throughout the world. For
instance, in Europe there are large differences between north and south. In the
north, differences between summer and winter are much higher than in the
south. In Bergen (Norway, 60.4°N) the ratio of global irradiation (total
irradiance on a horizontal surface on Earth) in June to global irradiation in
December is 40:1, whereas in Lisbon (Portugal, 38.72°N) this ratio is only
3.3:1. Central and northern Europe have annual global irradiation values of
between 700 kWh/(m
2
year) and 1000 kWh/(m
2
year). In southern Europe
this irradiation can be more than 1700 kWh/(m
2
year) and in desert regions of
