Overview Last Friday was the 75th anniversary of the release of "The Wizard of Oz" which was the first movie to depict an authentic looking tornado using improbable “1930’s style” special effects. Through the decades, this all-time classic has inspired movie-goers and “weather weenies” alike with the scene of a twister lifting Dorothy’s home into the sky over rural Kansas farm land.
Background The movie was based on a novel called "The Wonderful Wizard of Oz" written by L. Frank Baum in the year 1900. The setting of the movie in rural Kansas and the name of its main character, Dorothy Gale, were not just random choices. Baum had been a newspaper editor in the "Dakota Territory” (now South Dakota) and recalled the story of twin tornadoes that destroyed the rural town of Irving, Kansas in May of 1879. The name of one of the victims of this tornado outbreak was found in a mud puddle - and her name was Dorothy Gale.
The tornado scene As far as the tornado scene is concerned, it is still regarded as incredibly realistic – even in today’s era of computer-generated special effects. The first attempt at a tornado by the movie’s special effects director, Arnold Gillespie, was to use a 35-foot tall rubber cone, but this turned out to be too rigid and simply wouldn’t move. Next, the special effects director recalled from his experience as a pilot (even had his own airplane) that wind socks at airports had the classic funnel-shape of a tornado. He decided to make a tornado out of muslin (plane woven cloth) which would allow it to twist, bend and move from side-to-side. He built a 35-foot long tapered muslin sock and connected the top of it to a steel gantry suspended at the top of the stage. The gantry alone cost more than $12,000 (in 1938 dollars) and was specifically built for the tornado by Bethlehem Steel. It was a mobile structure similar to those used in warehouses to lift heavy objects and could travel the entire length of the stage. The bottom of the sock disappeared into a slot on the stage floor where it connected to a rod which came up through the base of the tornado to pull it from side-to-side. By moving the gantry and rod in different directions, the tornado appeared to "snake" across the stage.
To produce the dust and debris that makes a real tornado visible, they used compressed air hoses to spray a powdery brown dust known as “Fullers Earth” from both the top and bottom of the funnel. The muslin sock was sufficiently porous that some of the dust sifted through giving a blur or softness to the material and a fuzziness to the edges so that it didn’t look like a hard surface.
Four or five feet in front of the cameras were two panels of glass on which gray balls of cotton (great for mammatus clouds) had been pasted. The two panels moved in opposite directions adding to the boiling sensation and, at the same time, they obscured the steel gantry and top portion of the tornado. Dense clouds of yellow-black smoke made from sulfur and carbon were injected onto the set from a catwalk above the gantry. The stage hands had no respirators and stayed up there breathing the stuff until they couldn't stand it. Many of them became ill and some coughed up black-yellow mucous even days after the tornado was photographed.
Once the tornado had been filmed, there was still plenty of work to be done. Rear- projection was used to transfer the previously shot tornado image onto a translucent screen while actors such as Dorothy were placed in front of it. Wind machines provided the big blow while stage hands threw dried leaves and other debris in the air. When the tornado came real close to the house at the end of the scene, more debris and dirt were added in the foreground to obscure the fake tornado while providing more realism. The tornado scene in "The Wizard of Oz" ended up costing more money than any other special effect in the movie. So essentially, "The Wizard of Oz" tornado was nothing more than a large tapered cloth sock with lots of wind and dirt thrown at it.
Awards "The Wizard of Oz" was nominated for six Academy Awards and won two including “Best Original Song” (Over The Rainbow), but it did not win an Oscar for its amazing special effects and it did not win the Oscar for “Best Picture”. That honor went to another famous movie from 1939 with coincidentally a “weather-related” name - "Gone with the Wind". For additional information, check out the Penn State Department of Meteorology “Weather World” video presentation by Dr. Jon Nese (http://www.meteo.psu.edu/~j2n/WxYz.htm).