Not OP, but I remember reports of https://en.wikipedia.org/wiki/Buncefield_fire explosion which wikipedia claims "Because of an inversion layer, the explosions were heard up to 125 miles (200 km) away".

In my original post I was referring to an explosion _inside_ Belgorod: https://www.reuters.com/world/ukraine-strikes-fuel-depot-rus... which may or may not be directly linked to the war; Ukraine has denied responsibility.