Transmutation Circle - Master Howl uses them too

I have been compiling information on transmutation circles...they seem to keep popping up everywhere I look close enough and recently I have found another example.

Howl's Moving Castle - Transmutation Circle

In the movie Howl's Moving Castle the wizard master Howl even uses a transmutation circle in order to make a massive change to his moving fortress. He has to use his fire demon familiar to initiate the the spell however this circle defines and contains the magical power needed to preform the spell.
It seems to me if these circles keep appearing across all sorts of different platforms...then possibly these symbols are the key to channeling the earths energy.

Howls Moving Castle - Transmutation Circle

This specific circles are not as detailed as the ones found in Full Metal Alchemist however if we look closely there are plenty of similarities to be found.