When would a rotor cloud be ahead of a Cb?

1) Which cloud type may indicate the presence of severe turbulence?

2) At the top of orographic waves, in mountainous regions, the cloud most likely to be encountered is:

3) In mid-latitudes, the tops of Cumulus are often limited by:

4) Stratus formed by turbulence will occur when:

5) When severe mountain waves are present, where would the area of most severe turbulence be located?