def _calculate_sunrise_hour_angle(self, solar_dec, depression=0.833):
        """Calculate hour angle for sunrise time in degrees."""

        hour_angle_arg = math.degrees(math.acos(
            math.cos(math.radians(90 + depression)) /
            (math.cos(math.radians(self.latitude)) * math.cos(
                math.radians(solar_dec))) -
            math.tan(math.radians(self.latitude)) *
            math.tan(math.radians(solar_dec))
        ))

        return hour_angle_arg
Calculate hour angle for sunrise time in degrees.