Phys.org July 25, 2024 A team of researchers in the US (NSF National Center for Atmospheric Research, industry) provided substantial evidence for significant impacts of turbulence on the evolution of cloud droplet size distributions and rain formation by comparing high-resolution observations of cumulus congestus clouds with state-of-the-art large-eddy simulations coupled with a Lagrangian particle-based microphysics scheme. Turbulence causes earlier rain formation and greater rain accumulation compared to simulations with gravitational coalescence only. The observed rain size distribution tail just above cloud base follows a power law scaling that deviates from theoretical scalings considering either a purely gravitation collision kernel or […]
Tag Archives: Atmospheric turbulence
New twists on tornadoes: Earth scientist studies why U.S. has so many tornadoes
Phys.org June 27, 2024 Central North America is the global hotspot for tornadoes, fueled by elevated terrain of the Rockies to the west and a source of warm, moist air from equatorward oceans. Based on this theory central South America, with the Andes to the west and Amazon basin to the north, should have a “tornado alley” at least as active as central North America. Central South America has frequent severe thunderstorms yet relatively few tornadoes. According to a team of researchers in the US (Purdue University, National Center for Atmospheric Researchers, (Boulder, CO), Stony Brook University, Colorado State University) […]
Insights narrow the gap between large-scale atmospheric models and microscale features of atmospheric winds
Phys.org April 26, 2022 Modeling anomalies referred to as grey zone, arise when the model resolution approximates the length scale of turbulence features while modeling the atmosphere. An international team of researchers (USA – Notre Dame, Saudi Arabia) leveraged a new set of one-way nested, full-physics multiscale numerical experiments to quantify the magnitude of the errors introduced at gray zone resolutions in a real-case application. The new set of experiments conducted in Saudi Arabia spanned a wide range of scales and strategies to suppress resolved convection at gray zone resolutions. Detailed analyses of their experiments showed that (i) grid-dependent convective […]
A new record for laser stability across atmospheric distances
Phys.org January 24, 2022 The propagation of laser through turbulent atmosphere is affected by wind and minor equipment vibrations. Researchers in Australia used a host of features to keep the beam stable, including temperature controls, noise reduction and automatic adjustments to the devices holding the equipment. The test involved sending a beam from a building to a site 1.2 kilometers away. The target consisted of a mirror to bounce the laser beam back to a device near the source of the laser. The beam was held in place for approximately five minutes. Once a long-distance means of sending laser signals […]
Record-breaking laser link could help us test whether Einstein was right
Science Daily January 22, 2021 An international team of researchers (Australia, France) combined phase stabilisation technology with advanced self-guiding optical terminals that allowed laser signals to be sent from one point to another without interference from the atmosphere. They demonstrated phase-stabilized optical frequency transfer over a 265 m horizontal point-to-point free-space link between optical terminals with active tip-tilt mirrors to suppress beam wander, in a compact, human-portable set-up. They could correct for atmospheric turbulence in 3D, that is, left-right, up-down and, critically, along the line of flight. According to the researchers if you have one of these optical terminals on the […]