clouds and manual update

hi all!
I've a problem rendering the clouds, they seems like a plane, with the borders too much defined...
maybe that the farplane of the camera is relatively small? (about 600) or not?

another thing:
if I want update caelum manually, without the framelistener, what I need to do?
this is ok?

mCaelumSystem->notifyCameraChanged(mCamera);
mCaelumSystem->updateSubcomponents(fTime);


thanks very much