FlightAware's MiseryMap is pretty cool too https://www.flightaware.com/miserymap/
Most of the time the red fills in counter-clockwise. Until it is over 50%, then the red fills in clockwise.
Lots of the map circles actually represent MULTIPLE airports. But they still "represent" them with a three letter code. Sometimes by the largest airport (ORD, SFO), sometimes by a non-airport code (NYC), and sometimes by the second largest (DFW is larger that DAL).
Someone's pet project needs some more love.
EDIT: This version looks less like a pet project: https://www.flightaware.com/live/airport/delays