it could be one of the 3 possible solutions already mentioned. the bearing in your alternator or smog could be causing the whining.
i would describe it most of the time as a noise resembling a supercharger, or slightly lower in pitch. again not all the time, but
most of the times i have heard bad acces. bearings. one way to check is to take your belt off, and start your car and listen for
the noise. if it is still there then it could be the dist. bushings such as silvergtstang94 was talking about, harmonic balancer is a
possibility, or possibly something inside the motor. if the noise isn't there, then one of your acces. is the culprit. O0