https://www.hkmet.net/calhi.html
H-index = -42.379 + 2.04901523*F + 10.14333127*rh - 0.22475541*F*rh - 6.83783*Math.pow(10,-3)*F*F - 5.481717*Math.pow(10,-2)*rh*rh + 1.22874*Math.pow(10,-3)*F*F*rh + 8.5282*Math.pow(10,-4)*F*rh*rh - 1.99*Math.pow(10,-6)*F*F*rh*rh; c1 = -42.379 c2 = 2.04901523 c3 = 10.14333127 c4 = -0.22475541 c5 = -0.00683783 c6 = -0.05481717 c7 = 0.00122874 c8 = 0.00085282 c9 = -0.00000199