On a hot summer day, heat waves can be seen rising from the asphalt. what type of heat transfer do the heat waves demonstrate?

What you see rising from the road ... and call "heat waves" ...
are rising currents of air.  The air that's been heated by
contact with the hot asphalt rises.  (Why ?  By being heated,
it becomes less dense than the other air around it, and the
buoyant force of being a less dense substance in a more dense
fluid makes it rise (float) ).

If we want to paint a complete picture, we can find all three
types of heat transfer going on here:

1). The air getting heated by direct contact with the hot road ==> conduction

2). The hot air rising through the cooler air around it  ==> convection

3). How the road got so hot in the first place  ==> radiation, from the sun