Thanks Jonas,
on the comments:
1 - The still is just a frame of the video
2 - They are volume particles but because it is straight on with no shadows from the avalanche to the ground, it looks 2D yet. There is no easy and reliable way to get just a shadow pass of the particles. I think I have a way of doing it but that would require another pass and some playing around.
4 - The particles are released on the speed of the emitter so when it lands it slows down and more particles are released plus the bounce sends them floating higher for that look.
5 - thanks. I am glad to have have figured out how to do this right. I think the snow debris up front still rolls too far too fast yet but that is just a matter of increasing friction. Now to get those stones to look right and to get good shadowing.
