By analysing spectra of meteors ablating in the atmosphere, one can infer the composition of their parent bodies (asteroids and comets). A challenge to the accurate composition inference comes from external factors: factors other than the parent body composition, which affect meteoroid-atmosphere interactions and hence influence meteor spectral appearances. External factors considered here were meteoroid entry speeds, ablation temperatures and yearly meteoroids' interaction in space. This research aimed to assess to what degree these external factors influence the appearance of meteor spectra and meteoroids’ composition retrieval from them. The analysis revealed a strong correlation between meteors' entry speeds and elements’ number densities; number densities of meteoric elements showed a proportional decrease with speed. Moreover, the study concluded that increases of meteor spectra line intensities with height strongly correlate with increase in the ablation temperature. Finally, significant changes in meteoroid composition were seen among meteors generated from the same parent body but observed over different years.