> hello, I'm a new user and for a project in class we're creating a scene of our
> choice, I want to create a scene of a storm, with lightning hiting the ground,
> a tornado and storm clouds in the sky. How could I create this?
> thank you
> 
> 
> 

That looks like an ambitious, and time consuming, project for someone 
that is learning.

For the clouds, normaly, you'd use some object filled with a mesia and 
use some pattern or function to modulate that media. The media to use in 
this case, is a scattering media. Watch out, your render time will get 
prety long. NEVER use the "intervals" keyword. Use "samples" instead to 
get smoother results. Keep it low during the early stages to keep the 
render times needed during the devlopment phase to a reasonable level. 
Increace the samples count for your close to and final renders.

For the lightning, you can also use some media, but emissive media. Use 
a cylinder filled with emissive media that use the cylindrical pattern 
to whitch you apply some turbulence. For this, you need to create the 
container around the origin then rotate, scale and translate it to the 
desired location.
Emissive media is the fastest rendering media.
Emissive media don't illuminate it's surrounding, it's just visible 
without any light shining on it nor any background to see it against.

If you want your lightning to illuminate the area, then, you'll need to 
add some light_source along it's path. Be sure to make those light 
fading light by adding fade_power 2 and fade_distance <some distance> to 
the deffinitions. (that's the "fast" way, but less acurate)
The Slow, but more acurate, way is to use radiosity with the "media on" 
option. This way, the emissive media can actualy illuminate it's 
surrounding. But, as I said, radiosity is slow! Also, there are many 
settable parameters whose function and effects are not always obvious or 
easy to set.

Now, the trick is to create and locate the containers to create your 
clouds, find the best, to your taste, pattern for the clouds. Tweak the 
turbulence to give your clouds a more convincing look.

You'll probably need a complex container filled by several medias and 
also, possibly medias with more than one dencitys.

If you are tight on time, may I suggest looking to some other kind of 
scene...



Alain

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