Calculate RH from temperature and dewpoint
Details
Based on equation 12 in Lawrence 2005, The Relationship between Relative Humidity and the Dewpoint Temperature in Moist Air A Simple Conversion and Applications. BAMS https://doi.org/10.1175/BAMS-86-2-225 R = 461.5 K-1 kg-1 gas constant H2O L enthalpy of vaporization linear dependence on T (p 226, following eq 9)