  We explored the impact that Doppler dimming and brightening effects from bulk
motions of solar prominences have on the formation of Lya, Ha, and MgII h line
profiles. We compared two schemes in which these effects manifest; when the
prominence is moving radially away from the solar surface (radial case), and
when the prominence is moving parallel to the solar surface (horizontal case).
To do this, we analysed 13,332 model profiles generated through the use of the
1D NLTE (i.e. departures from Local Thermodynamic equilibrium) radiative
transfer (RT) code Promweaver, built on the Lightweaver NLTE RT framework to
mimic the behaviour and output of the 1D NLTE RT code PROM. We found that
horizontal velocities are just as, or more important than radial velocities.
This demonstrates that horizontal velocities need to be accounted for when
attempting to do any sort of forward modelling.
