Unlike the more common double-rainbow, which consists of two separate and concentric rainbow arcs, the elusive twinned rainbow appears as two rainbows arcs that split from a single base rainbow. Sometimes it is even observed in combination with a double rainbow.
It is well-known that rainbows are caused by the interaction of sunlight with small water drops in the atmosphere; however, even though the study of rainbows can be traced back more than 2,000 years to the days of Aristotle, their complete and often complex behavior has not been fully understood until now.
"Everyone has seen rainbows, even double-rainbows, and they continue to fascinate the scientific community," said Dr. Wojciech Jarosz, co-author of the paper and Research Scientist at Disney Research, Zürich. "Sometimes, when the conditions are just right, we can observe extremely exotic rainbows, such as a twinned rainbow. Until now, no one has really known why such rainbows occur."
Jarosz and the international team of researchers studied virtual rainbows in simulation, considering the physical shape of water drops, and their complex interactions with both the particle and wave-nature of light. The key to the twinned rainbow mystery, Jarosz said, is the combination of different sizes of water drops falling from the sky.
"Previous simulations have assumed that raindrops are spherical. While this can easily explain the rainbow and even the double rainbow, it cannot explain the twinned rainbow," he said. Real raindrops flatten as they fall, due to air resistance, and this flattening is more prominent in larger water drops. Such large drops end up resembling the shape of hamburgers, and are therefore called "burgeroids".
"Sometimes two rain showers combine," Jarosz said. "When the two are composed of different sized raindrops, each set of raindrops produces slightly deformed rainbows, which combine to form the elusive twinned rainbow." The team developed software able to reproduce these conditions in simulation and the results matched, for the first time, twinned rainbows seen in photographs. The team also simulated a vast array of other rainbows matching photographs.
The team's discovery was unintentional. "Initially the goal was to better depict rainbows for animated movies and video games and we thought rainbows were pretty well understood," said Jarosz. "Along the way we discovered that science and current simulation methods simply could not explain some types of rainbows. This mystery really fueled our investigations." The researchers now see potentially wider application of their method beyond computer graphics, speculating that, some day, accurate rendering models of atmospheric phenomena, like the one they developed, could have impact in areas such as meteorology for deducing the size of water drops from videos or photographs.
The research findings by will be presented Aug. 8 in the "Physics and Mathematics for Light" session at SIGGRAPH 2012, the International Conference on Computer Graphics and Interactive Techniques at the Los Angeles Convention Center. For a copy of the research paper, please visit the project web site at http://zurich.disneyresearch.com/~wjarosz/publications/sadeghi11physically.html.
About Disney Research
Disney Research is a network of research laboratories supporting The Walt Disney Company. Its purpose is to pursue scientific and technological innovation to advance the company's broad media and entertainment efforts. Disney Research is managed by an internal Disney Research Council co-chaired by Disney-Pixar's Ed Catmull and Walt Disney Imagineering's Bruce Vaughn, and including the directors of the individual labs. It has facilities in Los Angeles, San Francisco, Pittsburgh, Boston and Zurich. Research topics include computer graphics, video processing, computer vision, robotics, radio and antennas, wireless communications, human-computer interaction, displays, data mining, machine learning and behavioral sciences.
Jennifer Liu | EurekAlert!
'Frequency combs' ID chemicals within the mid-infrared spectral region
16.03.2018 | American Institute of Physics
Fraunhofer HHI have developed a novel single-polarization Kramers-Kronig receiver scheme
16.03.2018 | Fraunhofer-Institut für Nachrichtentechnik, Heinrich-Hertz-Institut, HHI
Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...
On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...
The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...
At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.
When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...
At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.
Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...
16.03.2018 | Event News
13.03.2018 | Event News
08.03.2018 | Event News
16.03.2018 | Earth Sciences
16.03.2018 | Physics and Astronomy
16.03.2018 | Life Sciences