Look at the physical geography near the respective fields.
EMA just to south east of the edge of Derbyshire Peak district and closer to the Pennines, so more sporting conditions due orographic effects, ducting etc.
BHX sits in relatively flatter terrain and further away from big lumpy bits of cumulo-granite.
Geostrophic wind 30 degrees greater and nearly twice as strong as the surface wind?
Wish I'd paid more attention when at skule, that's worn me out so back to the darkened room!
