Zonnestraling in Nederland - Knmi

S U M M AR Y
In this book both physical and statistical aspects of solar radiation in the Netherlands are
discussed. Emphasis is put on available data of global, diffuse, direct-beam and long-wave
radiation of the climate.
After a brief introductory chapter, the second chapter deals with the properties of solar
radiation in the atmosphere at an elementary level. The electromagnetic spectrum is introducedin
section 2.1.
Section 2.2 starts with the physical aspects of absorption, emission and scattering of radiation.
After that, attention is paid to absorption and scattering in the atmosphere and to the
energy budget of the Earth-atmosphere system. Formulas are given for absorption, scattering
and extinction and the optical mass is introduced.
Section 2.3 is devoted to the turbidity. Linke's turbidity factor and the turbidity formulas
according to Angström and Schüepp are reviewed.
The concept of transmittance to calculate direct-beam radiation is given in section 2.4. Data
for absorption by ozone, water vapour and other gases, as well as Rayleigh scattering and
absorption by aerosols are included in this section. A short subsection is devoted to the
reflected radiation or the albedo of various surfaces.
In section 2.5 an empirical equation is introduced, estimating the incoming long-wave
radiation according to Swinbank. This has been used to calculate the long-wave radiation
climate in the Netherlands.
In chapter 3 attention is paid to radiation instruments and to the network for radiation and
sunshine measurements in the Netherlands. The pyrheliometer for measuring direct-beam
radiation is discussed, with the Angström and Linke-Feussner pyrheliometers as examples of
instruments which require calibration, and the cavity pyrheliometer as an example of a selfcalibrating
instrument. Measurements of the direct-beam radiation at De Bilt have been made
with the Linke-Feussner instrument.
Kipp and Eppley pyranometers used for measuring global radiation in the Netherlands are
discussed. A short subsection is devoted to the diffusometer for measuring the diffuse radiation.
Next, the Campbell-Stokes sunshine recorder to measure the duration of sunshine and the
new automatic sunshine recorders of Soni and Haenni are briefly described. Sunshine observations
with the Campbell-Stokes recorder commenced in 1899 at De Bilt. At present there
are 35 stations in the network (Table 3.2 and Figure 3.9).
Global radiation observations commenced in 1957 at De Bilt. Ten years later the network
consisted of 5 stations. Now there are 19 stations where global radiation is measured (Table
3.1 and Figure 3.8). Direct radiation has been measured at De Bilt since 1971 and diffuse
radiation since 1986. Also, from 1979 to 1981 the global radiation was measured at Cabauw
for 12 differently inclined surfaces.
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