When a Stargate first activates an unstable vortex forms, destroying anything in it's way. This has been nicknamed the kawoosh by the show's producers. In "Stargate SG-1, the illustrated companion season 1 and 2" (titan books) written by Thomasina Gibson, visual effect producer of the series James Tichenor explains the 'Kawoosh' effect. "It's such a dynamic turbulent effect it's almost impossible for us to build in CG (Computer Generation.) We have tried to do it a couple of times, because wanted to do more with it, and have different camera angles and what have you, but it never turns out quite as realistic. What we actually did to shoot the 'Kawoosh' was prepare a tank of water, modelled on what they did to create the effect in the feature film, and blast it with a little air cannon. The high-powered air mover had a very focussed noozle exhorting major pounds per square inch of air into a very, very small point. We set that up in the water tank, and used gravity to our benefit. We shot the air cannon down and placed the camera shooting straight up at one hundred and twenty frames per second. So we got the effect of this funnel of water coming straight through" "The whole shot took about three days to film. Working in GVFX's model shop in Toronto, they knew exactly which angles they needed, took the camera down, made the environment as black as possible and just started shooting. They ended up with about ten different angles, which we still use this day. Every time we need a 'Kawoosh' in an episode we refer back to the ones we shot almost five years ago. We composite them into new shots and always have to very carefully match the perspective angles, so it takes a bit of time to get right."