Modification of the model for black and white mulching
Models to calculate temperature regimes under black and white opaque films can be
made by making minor changes in the model. The only difference in the program
between these two model and that for clear film is the calculation of transmissivity and
absorptivity of films. Transmissivity and absorptivity of clear film are calculated by the
equations given in the preceding section, but those for opaque black and white films are
given by arbitrary function generators based on experimental observations. The different
part is shown in the MACRO function FRSNL(T), in Fig. 6.5
The Arbitrary Function GENerator (AF GEN) is a very convenient tool for generating
a non-linear relationship based on observation values in the following way.