What are the flashing lights on top of school buses for?

It's visible in fog. The red/yellow ones don't penetrate that weather condition. It's also seen for a farther distance than regular lights & will catch a 'highway hypnotised" person's attention (notice that most stoplights/traffic lights now have these strobes as well).

What are the strobe lights for. Aircraft have strobe lights, right? What are the strobe lights on aircraft for? Dancing floors have strobe lights, aren't they annoying. For me, the buses have strobe lights because when I see that light I know its a bus, just like when I'm in an airport and see an airplane, I know its an airplane.

the flashing light on top of the bus seems to be used for many different purposes. Yes, its used for the fog (to see and be seen), but I know in my hometown that light is also used to trigger stop lights. Sort of like Police, Fire, etc, there is a pulsing light on these vehicles which trigger the stop light to turn in their favor.

To make drivers aware of a school bus and be prepared to stop if necessary. It's just fair warning of a bus and to watch for the yellow lights or stop sign/red lights.

To advise other motorists that children could be alighting or getting off the bus, it is a safety mechanism

For better visibility during poor weather conditions.

Increased safety. Clearly it works to make you aware of school busses, since it is annoying you.