def dew_point_from_db_rh(db_temp, rh):
    """Dew Point Temperature (C) at Dry Bulb Temperature db_temp (C) and
    Relative Humidity rh (%).

    Note:
        [1] J. Sullivan and L. D. Sanders. "Method for obtaining wet-bulb temperatures by
        modifying the psychrometric formula." Center for Experiment Design and Data
        Analysis. NOAA - National Oceanic and Atmospheric Administration.
        http://www.srh.noaa.gov/epz/?n=wxcalc_rh
    """
    es = 6.112 * math.e**((17.67 * db_temp) / (db_temp + 243.5))
    e = (es * rh) / 100
    td = (243.5 * math.log(e / 6.112)) / (17.67 - math.log(e / 6.112))
    return td