Particle Question: Why don't my particles emit downward?

I'm experimenting with a sample particle script that I got off of Wiki and I'm not getting the effect that I think I should be getting. I believe that when I use the PSYS_SRC_PATTERN_EXPLODE flag, I should see particles emitted in every direction. Instead I am only getting particles from the upper hemisphere of my object. Does anyone have any suggestions?

I have screenshots of the effect and the exact script I used posted on my blog www.secondlifehowto.com.

Check these two lines in your script:

float outerAngle = 1.54;    // Outer angle for all ANGLE patterns
float innerAngle = 1.55;    // Inner angle for all ANGLE patterns

Those variables set the angle of particle radiation, in radians, not degrees. Change them both to 0.0 to radiate in all directions.

I tried that, and it didn't do it, and I wouldn't think it would because those parameters only effect angle emissions not explosions.

I also tried to push the particles down with the following change to my script:
vector push = <0,0,-10>; // Force pushed on particles

This resulted in the particles indeed being forced down in the -Z direction but the particles never went lower than the plane in which my object floated. In otherwords instead of the particles going down and bouncing on the ground as I would expect, the particles are emitted from the upper hemisphere of the block, then are forced down and bounce on an imaginary barrier several meters off the ground that bisects my floating block.

That is how "bounce" is supposed to work. Per the wiki:
"PSYS_PART_BOUNCE_MASK particles bounce off object's z-axis height "
Turn off "bounce" if you want the particles to go to the ground.

Angles have no effect when using the EXPLODE pattern; only the ANGLE patterns.

Jesse has the right of it. You have BOUNCE turned on; no particle will go below the Z=0 plane of the emitter (which is at the geometric center of the prim), even if the pattern would otherwise tell it to.

Just in case you didn't know. Here is the wiki page that tells what each of the particle settings do:

http://www.lslwiki.com/lslwiki/wakka.php?wakka=llParticleSystem

Getting rid of the bounce flag did it. That was dumb, I should have read about the bounce flag more carefully. The way I was reading it I thought it would bounce off the ground.