[R] Variance of multiple non-contiguous time periods?

[CJ Davies]

I am trying to show that the red line ('yaw') in the upper of the two 
plots here;

http://i.imgur.com/N4Xxb4f.png

varies more within the pink sections ('transition 1') than in the light 
blue sections ('real').

I tried to use var.test() however this runs into a problem because 
although the red line doesn't vary much *within* any particular light 
blue section, it does vary a lot *between* light blue sections.

For example, in the light blue section around t=90 the red line doesn't 
move much & likewise in the light blue section around t=160 the red line 
doesn't move much. But between these two sections the red line has moved 
substantially.

So if I simply subset the data according to pink/light blue & then put 
those resultant subsets into var.test(), the answer does not show the 
relationship that I want it to.

Can anybody shed some light on a sensible method of solving this?

Regards,
CJ Davies