Rain and Snow photographed going upwards - help

I really hope someone can explain this one to me.
I have a Canon 350D with a Canon Speedlight 580EX.
I took a picture of the snow falling and it appeared to be going upwards. No problem, I set things to 2nd curtain sync and it still appears going upwards?
Hmmm... maybe my 2nd curtain sync isn't working so I did the below test, it worked fine in the test, however, falling rain, falling drips and snow still appear to be going upwards... Anyone have any ideas on this one? or has anyone else experienced this?

Experiment: I tied my dogs toy to my ceiling lamp and then tied some fluffy yarn to the toy to give it a tail so visually I would know what direction it was going. I lifted the toy high into the air and let it swing. Shot one with 1st curtain sync and the other with 2nd curtain sync and all was well... just not rain or snow? I don't get it...

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Can you post your snow and/or rain pictures instead? That would be more helpful than posting pictures you're not having a problem with.

Thanks Leo... good point.
Sorry..

1st photo is standard settings 350D 1st Curtain Sync and 580EX on standard ETTL

2nd photo is 350D set to 2nd curtain sync and the 580EX set to 2nd Curtain sync.

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Since there is very little ambient light in the images, it really doesn't matter if you use first or second curtain. Ambient light is required to create a ghosting affect in front of or behind the flash exposure.

Here's my best guess: Since the background is distant and quite underexposed, I'm guessing the flash fired at full power in a vain attempt to expose the images. At full power, the intensity of the flash peaks quickly and then drops gradually as the capacitor empties. So as the rain drops travel downward, the diminishing power of the flash creates a trail below the brightly exposed drops above.

At lower power settings, the flash duration is shorter and the flow of electricity is stopped abruptly so you won't see so much of a tail. Try setting the flash manually at something like 1/8 power and see what you get.

Curtis N you are the man !

Thank you very much for that explanation. Wow, I shot the above shots at 1/60 and the below shot was done at 1/30 and 1/8 flash power. I didn't even think about the ambient light play on this whole thing

Thank you, thank you, thank you ! I find it amazing that the streaks in the above pictures are all flash dissipation... wow...

Because of you I won't be having any headaches trying to figure this one out.

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If you want to have fun with second curtain, shoot a moving light source, like car headlights (just keep the camera still and don't try to pan with it).