When do queen bees mate?

When a new queen emerges from the pupal cell she will spend a few days in the hive, then after usually a week to ten days after emerging, on a fine, warm day she will leave the hive on a mating flight. She will usually fly at about ten metres above the ground towards an area where drones from the surrounding area congregate. The drones will start to pursue the queen at which point she will fly at an increasing altitude with the drones chasing her. Eventually she will be mated on the wing by several drones. After this she will return to the hive and will start laying eggs a couple of days later.
As a side point, we know about the drone congregation areas, but although successive generations tend to use the same areas we don't know why the drones choose these particular places to gather.