function ccm3_cloud_ice_re_param_function, p_ratio


; Reference Kiehl et al., Journal of Climate, June 1998, pg 1133, eqn 6

; p_ratio is the pressure/surface_pressure

pi_low=0.0 & pi_high=0.4 & rei_min=10. & rei_max=30.

if p_ratio gt 0.4 then begin
    re=30.
endif else begin
    re=rei_min-((rei_min-rei_max)*(((p_ratio)-pi_low)/(pi_high-pi_low)))
    if re lt rei_min then re=rei_min
endelse

return, re

end