change effect in a motion tween

[F6]

I have a cloud moving across the stage with lightning on a seperate layer.
I want to have the cloud move across, then suddenly "light up" (altering the effect, brightness) for a few frames, then go back to normal. How do I do this?

I tried adding a keyframe, but then it just gradually lights up from frame 1.

[Iodem]

In the middle of the cloud's motion tween frames (or whenevr you want it to light up), add a key frame, skip a frame or two, add another, skip another frame or two, and add one more. Should look something like:

[o]<-------->[o]<->[o]<->[o]<-------->[o]

The middle frame, the one sandwiched between the other four, if where you want to modify the effect panel to make it lighter.

Remember, it doesn't matter where the three frames are, and how far you space them apart alters the time of the 'light up'.

[F6]

Wow! I never would've figured that one out. I was following the motion tween on a seperate layer and putting darkened instances of clouds in seperate keyframes! That works too if you have about an hour to kill.
It worked great -- thanks!