limits to vector control

Accelerator had only just thought up that method and it had caused more destruction
than he had imagined.
But it was still incomplete. Unlike his automatic reflection, he had to think about the
original vector and the altered vector when he was altering vectors under his own will.
Wind, the flow of the atmosphere, required complex calculations that involved chaos
theory, so it could not be completely predicted without the use of Tree Diagram.
He doubted that the flow of the entire world’s atmosphere could be calculated in a single
human’s head.
He had only managed to manipulate the wind within Academy City and that had still
been imperfect.

- Toaru Majutsu no Index Volume 3, Chapter 4 Part 7