Well, it wouldn't really be the wake...because that is the turbulence in the water behind the ship. But I still believe your point (in all seriousness) is very well taken.my guess is the color smoke is used to study wake turbulence. kinda like in a wind tunnel.
It could very well be an effort to model wind conditions behind the carrier in various given situations (ie. speed of the carrier, direction of the wind, speed of the wind, and the resulting air flow behind the carrier that incoming/landing aircraft would have to deal with.