%N pvapsat %F $MIR/src/subs/refract.for
%D Compute sky brightness and opacity of a model atmosphere.
%P rjs
%: utilities
%B
        real function pvapsat(T)

        implicit none
        real T

  Determine the saturation pressure of water vapour.

  Inputs:
    T          Temperature (Kelvin).
  Output:
    pvatsat    Vapour stauration pressure (Pascals).

  Reference:
    Waters, Refraction effects in the neutral atmosphere. Methods of
    Experimental Physics, vol 12B, p 186-200 (1976).
