def net_in_sol_rad(sol_rad, albedo=0.23):
  """ Compute net incoming shortwave solar radiation after Eq. 33 in Allen et al. 1998.

  Parameters
  ----------
  sol_rad: array
    Solar radiation in [MJ·m-2·d-1]. Either calculated from sunshine duration or temperature.
  albedo : scalar 
    Proportion of gross incoming solar radiation that is reflected by the surface.
    Albedo can be as high as 0.95 for freshly fallen snow and as low as 0.05 for wet bare soil. 
    A green vegetation over has an albedo of about 0.20-0.25 (Allen et al, 1998).

  Returns
  -------
  array
    Net incoming solar radiation in [MJ·m-2·d-1].
  
  """  
  return (1 - albedo) * sol_rad