Solar flares and eruptions are the most energetic phenomena in the solar system. Theoretical interpretations of solar flares in 2D were summarized in 1960s in so-called CSHKP model, which has been used as a standard model of solar flares ever since. Using this model, researchers were able to interpret basic morphological features present in solar flares such as coronal mass ejections (CMEs), flare loops, X-ray sources etc. The standard model on solar flares, however, lacks an information on morphology of solar flares along the arcade of flare loops. There, footpoints of flare loops are observed in UV and EUV spectra as flare ribbons, which play a key role during magnetic reconnection in 3D.

Here we present interpretation of elongation of flare ribbons and motion of flare kernels in 3D using the model of solar flares and eruptions in 3D of Aulanier et al. (2010), using observations of eruption observed on 2012 August 31st. We also focus on analysis of an eruptive flare (X8.2) by Yan et al. (2018) and point out why the authors were wrong about interpreting the event using the standard 2D model.