Table 2 Description of the physical and mathematical quantities of the data used in the study and their relation with the study purpose

Atmospheric pressure \(\left[ {mb\;or\;hPa} \right]\)

\(p = h{\kern 1pt} \rho {\kern 1pt} g_{0}\)^a

Pressure anomalies were shock waves, which were generated by HT-HH volcano eruption at certain times

Speed \(\left[ {km\,h^{ - 1} } \right]\)

\(\upsilon_{0} = z_{0} /t_{0}\)

Speed was calculated in order to describe the physics of the shock wave propagation

Average speed \(\left[ {km\,h^{ - 1} } \right]\)

\(\upsilon_{sr} = z_{u} /t_{u}\)

This physical quantity was used in order to describe the physics of the second shock wave and the “first shock wave return”

Orthodromic distance \(\left[ {km\;or\;nm} \right]\)

\(\cos z = \sin \varphi_{1} \cdot \sin \varphi_{2} + \cos \varphi_{1} \cdot \cos \varphi_{M2} \cdot \cos \left( {\lambda_{2} - \lambda_{1} } \right)\)

This mathematical quantity was used in order to calculate distance between MS in Serbia and HT-HH volcano, as well as to calculate the speed of the of the shock wave propagation; further on, this quantity was used in order to describe the direction of the shock wave propagation