Charles, I can answer your question pretty quickly.  It is really just
a matter of how sound travels and how light travels.  You can see
lightening and hear no thunder because, in general, thunder only
travels 10 to 20 miles.  Lightening, on the other hand, can be seen
from outerspace!  So if you have an unobstructed view, you could expect
to see lighting from hundreds of miles away. 

As for hearing thunder but seeing no lightening, it is again the way
the two travel.  You could easily hear the thunder caused by a cloud to
cloud strike of lightening that is completely obscured from the ground
because of heavy cloud cover.  

One thing is sure:  thunder and lightening go hand in hand.  Just
because you see only the one, doesn't mean the other one wasn't there.  

df wrote:

>charles browning of calif. usa asks:
>Your answer on thunder/lightning was 
>excellent; well done. But could you 
>please tell us why sometimes you hear 
>thunder and see no lightning, and see 
>lightning but hear no thunder?  Help!