Cloud Tank Effects


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This essay is a short analysis of the atmospheric effect of Cloud Tanks, and its use and innovation in Steven Spielberg’s 1977 film Close Encounters of the Third Kind

Author: Alberto D’Onofrio

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Anyone would find a tank of water and imagine what kind of fish would swim in it. A visual effects artist, however, would imagine what kind of Cloud Tank effect he or she could create. A Cloud Tank is a water tank that is used to create the atmospheric effect of the formation of clouds. The cinematic effect is consequently named the Cloud Tank effect. The effect’s process begins with filling a water tank halfway with saltwater which is then layered with a thin plastic sheet. Fresh water is poured over the thin layer of plastic to fill the rest of the tank. This leaves the visual effects artist to remove the thin layer of plastic to reveal what seems to be a single body of water, but is really two layers of different densities: salt water and fresh water. Finally, paint is injected into the tank and it flows through the water, forming an organic cloud figure (Bjerre, 1). This is an effect and process first developed by special effects artist Douglas Trumbull during his work on Steven Spielberg’s 1977 film Close Encounters of the Third Kind.

As Douglas Trumbull explains in The Making of Close Encounters of the Third Kind (Bouzereau, 2001), it was Steven Spielberg’s idea to have the clouds as a hiding space for UFOs until the Mothership would emerge out of the clouds. Trumbull and his team began by adding white paint into a full tank of water.  Experimenting with this concept, they determined the effectiveness of filling the tank with both fresh water and salt water. Trumbull explains that this enabled a difference in gravity that was invisible to the camera, which allowed the paint to develop a flat bottom and cloud-like atmosphere when forming through the fresh water. This process is described as laborious; Trumbull and his team only managed to shoot one Cloud Tank effect per day, maybe two if they were lucky. Scott Squires, an assistant to Douglas Trumbull in Close Encounters of The Third Kind, expands on the difficult process in recent personal accounts (Squires, 1). A 2000 gallon glass tank was used that was approximately seven feet tall, seven feet wide and four feet deep which would have to be emptied and refilled after every shot.

After the Cloud Tank effects were captured on film, they were composited onto the rest of the film, a process of layering multiple images from separate sources as one (Prince, 59). As Douglas Trumbull expands on this procedure, he states that while most of the film was shot on 35mm Anamorphic, all the visual effects, including the Cloud effects, were shot on 65mm. If the visual effects were shot on 35mm, the film would degrade when composited with the film. To compensate for this, the Cloud Effects were shot on film double the size and they optically combined the visual effects with the film on 65mm. Later, they reduced the composited film to 35mm Anamorphic.

The success of Cloud Tank effects as an atmospheric quality in Close Encounters of Third Kind inspired Steven Spielberg and other filmmakers to continue utilizing the effect for intense, climactic and dramatic scenes in Raiders of the Lost Ark (Spielberg, 1981), Poltergeist (Hooper, 1982), and Independence Day (Emmerich, 1996). Although Independence Day used this technique, it was manipulated by computer technology that was developed in the late nineties (Bjerre, 1), technology that ultimately ended the practical effect and began the CGI rendering of Cloud Tank effects, a process that would be less laborious and more controlled. Although the practical effect is obsolete in the industry, a young-generation of filmmakers, including myself, is seen experimenting with Cloud Tank effects and posting tutorials for other aspiring filmmakers on the Internet. Like most practical effects, the pure joy of experimenting with Cloud Tanks is something a computer cannot match or take away.


Bjerre, David. “The Single-Minded Movie Blog: Old School Effects: The Cloud Tank.” The Single-Minded Movie Blog: Old School Effects: The Cloud Tank. N.p., n.d. Web. 03 Oct. 2013.

Close Encounters of the Third Kind. Dir. Steven Spielberg. Columbia Pictures. 1977. DVD.

“Films | Douglas Trumbull – Immersive Media and Visual Effects.” Films | Douglas Trumbull – Immersive Media and Visual Effects. N.p., n.d. Web. 03 Oct. 2013.

Independence Day. Dir. Roland Emmerich. 20th Century Fox. 1996. Online.

Poltergeist. Dir. Tobe Hooper. Metro-Goldwyn-Mayer. 1981. Online.

Prince, Stephen. Digital Visual Effects in Cinema: The Seduction of Reality. New Brunswick, NJ: Rutgers UP, 2012. Print.

Raiders of the Lost Ark. Dir. Steven Spielberg. Paramount Pictures. 1981. Online.

Squires, Scott. “Effects Corner.” : Cloud Tank Effect. N.p., n.d. Web. 03 Oct. 2013.

The Making of Close Encounters of the Third Kind. Dir. Laurent Bouzereau. Columbia Tristar Home Entertainment. 2001. DVD.


One thought on “Cloud Tank Effects

  1. Pingback: SINK – Complete Aesthetics Project & Reflection | Brianna Ng

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