Refraction:
a. causes light to "bounce off a surface
b. causes blueshift
c. is caused by light moving through different substances
d. is caused by the source of the waves moving closer to the receiver
e. is caused by light moving around a corner
Refraction is caused by any wave crossing the boundary out of one substance and into another one. The two different substances may be no more than two parcels of air at different temperatures.
