And no raindrop can fall faster than its "terminal speed"--its speed when the downward force of gravity is exactly the same as the upward air resistance. Now, a team of U.S. and Mexican researchers has found that it ain't necessarily so.
Some smaller raindrops can fall faster than bigger ones. In fact, they can fall faster than their terminal speed. In other words, they can fall faster than drops of that size and weight are supposed to be able to fall. And that could mean that the weatherman has been overestimating how much it rains, the scientists say.
"Existing rain models are based on the assumption that all drops fall at their terminal speed, but our data suggest that this is not the case," explains Raymond Shaw, a physicist at Michigan Technological University in Houghton and a member of the research team. "If rainfall is measured based on that assumption, large raindrops that are not really there will be recorded."
understanding of the physics of rain and improve the accuracy of weather measurement and prediction.
Shaw, Alexander Kostinski, also of Michigan Tech, and Guillermo Montero-Martinez and Fernando Garcia-Garcia of the Universidad Nacional Autonoma de Mexico (National University of Mexico) in Mexico City, will publish their findings Saturday, June 13, in the American Geophysical Union's journal, Geophysical Research Letters.
To study the raindrops, they used optical array spectrometer probes and a particle analysis and collecting system. They also modified an algorithm, or computational formula, to analyze raindrop sizes.
The scientists found clusters of raindrops falling faster than their terminal speed, and as the rainfall became heavier, they saw more and more of these unexpectedly speedy drops. Images revealed that the "super-terminal" drops come from the break-up of larger drops, which produces smaller fragments all moving at the same speed as their parent raindrop and faster than the terminal speed predicted by their size.
"In the past, people have seen indications of faster-than-terminal drops, but they always attributed it to splashing on the instruments," Shaw says. He and his colleagues took special precautions to prevent such interference, including collecting data only during extremely calm conditions.
This research was supported in part by the National Science Foundation.Title:
Alexander B. Kostinski: Department of Physics, Michigan Technological University, Houghton, Michigan, USA;
Raymond A. Shaw: Department of Physics, Michigan Technological University, Houghton,Michigan, USA;
Fernando Garcia-Garcia: Posgrado en Ciencias de la Tierra y Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Circuito de la Investigacion Cientifica, Mexico City, Mexico.Citation:
Res. Lett., 36, L11818, doi:10.1029/2008GL037111.
Peter Weiss | American Geophysical Union
NASA sees the end of ex-Tropical Cyclone 02W
21.04.2017 | NASA/Goddard Space Flight Center
New research unlocks forests' potential in climate change mitigation
21.04.2017 | Clemson University
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...
Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.
A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
21.04.2017 | Physics and Astronomy
21.04.2017 | Health and Medicine
21.04.2017 | Physics and Astronomy