How Does the Envelope of a Light Wavepacket Change at a Media Interface?

[harvey_dog]

Hi, I've had trouble finding an answer to this question and was wondering if anyone could help.

What happens to the envelope of a wavepacket of light when it crosses the interface between two media?

I know that the field of the wavepacket will be continuous across the boundary, but does the same apply to the envelope?

 

[Meir Achuz]

The B field is not continuous.