In-Universe:
The U.S.S. Defiant leaves the plasma fields in a hurry to confront Michael Eddington.
Production:
"The rolls and thrusters bursts Dax announced were brought to life by Gary Hutzel's crisp motion control photography of the Defiant and DS9."
— Cinefantastique Volume 29, Numbers 6/7 (Page 45)
Gary Hutzel ditched the CGI Badlands effect from Voyager and created an all new one.
— Star Trek DS9 Companion (Page 420)