The Concentration of Magic

Henrik raised his hand to his eyes to try to give shade to them.  For the last several minutes, the air had a brightness and haze to it that belonged on a summer's midday, not the wet and chill spring morning they were enduring.  Indeed, it felt as if they were at sea as the prairie's grasses undulated around them.  And just as at sea, they kept their eyes up searching for a tower that might provide the guidance that would save their lives.... 

I have been toying with the idea of how magic works in MW.  I like the idea of areas of the world that are naturally more "heavy" with magic than others, particularly special types of magic.  Such as special areas of grasslands being a convergence of divination magic or the coast being a place of transmutation.  

Magic could flow along ley lines as rivers, but these special places would be unique pools that coalesce certain flavors of magic.  Such a concentration could produce a physical effect of seeing the magic in the air without the aid of the Detect Magic spell.

I don't want to replicate the 5-color wheel that is used by certain card games.  The needs of MW are much more complex than that.