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Articles 1 - 15 of 15
Full-Text Articles in Physics
Winding Around Non-Hermitian Singularities, Qi Zhong, Mercedeh Khajavikhan, Demetrios Christodoulides, Ramy El-Ganainy
Winding Around Non-Hermitian Singularities, Qi Zhong, Mercedeh Khajavikhan, Demetrios Christodoulides, Ramy El-Ganainy
Department of Physics Publications
Non-Hermitian singularities are ubiquitous in non-conservative open systems. Owing to their peculiar topology, they can remotely induce observable effects when encircled by closed trajectories in the parameter space. To date, a general formalism for describing this process beyond simple cases is still lacking. Here we develop a general approach for treating this problem by utilizing the power of permutation operators and representation theory. This in turn allows us to reveal a surprising result that has so far escaped attention: loops that enclose the same singularities in the parameter space starting from the same point and traveling in the same direction, …
Fine-Scale Droplet Clustering In Atmospheric Clouds: 3d Radial Distribution Function From Airborne Digital Holography, Michael L. Larsen, Raymond Shaw, Alexander Kostinski, Susanne Glienke
Fine-Scale Droplet Clustering In Atmospheric Clouds: 3d Radial Distribution Function From Airborne Digital Holography, Michael L. Larsen, Raymond Shaw, Alexander Kostinski, Susanne Glienke
Department of Physics Publications
The extent of droplet clustering in turbulent clouds has remained largely unquantified, and yet is of possible relevance to precipitation formation and radiative transfer. To that end, data gathered by an airborne holographic instrument are used to explore the three-dimensional spatial statistics of cloud droplet positions in homogeneous stratiform boundary-layer clouds. The three-dimensional radial distribution functions g(r) reveal unambiguous evidence of droplet clustering. Three key theoretical predictions are observed: the existence of positive correlations, onset of correlation in the turbulence dissipation range, and monotonic increase of g(r) with decreasing r. This implies that current theory captures the essential processes contributing …
Turbulence Induced Cloud Voids: Observation And Interpretation, Katarzyna Karpinska, Jonathan F. E. Bodenschatz, Szymon P. Malinowski, Jakub L. Nowak, Steffen Risius, Tina Schmeissner, Raymond Shaw, Holger Siebert, Hengdong Xi, Haitao Xu, Eberhard Bodenschatz
Turbulence Induced Cloud Voids: Observation And Interpretation, Katarzyna Karpinska, Jonathan F. E. Bodenschatz, Szymon P. Malinowski, Jakub L. Nowak, Steffen Risius, Tina Schmeissner, Raymond Shaw, Holger Siebert, Hengdong Xi, Haitao Xu, Eberhard Bodenschatz
Department of Physics Publications
The phenomenon of cloud voids, i.e., elongated volumes inside a cloud that are devoid of droplets, was observed with laser sheet photography in clouds at a mountain-top station. Two experimental cases, similar in turbulence conditions yet with diverse droplet size distributions and cloud void prevalence, are reported. A theoretical explanation is proposed based on the study of heavy inertial sedimenting particles inside a Burgers vortex. A general conclusion regarding void appearance is drawn from theoretical analysis. Numerical simulations of polydisperse droplet motion with realistic vortex parameters and Mie scattering visual effects accounted for can explain the presence of voids with …
Data Supporting The Paper "Turbulence Induced Cloud Voids: Observation And Interpretation", Katarzyna Karpinska, Jonathan F. E. Bodenschatz, Szymon P. Malinowski, Jakub L. Nowak, Steffen Risius, Tina Schmeissner, Raymond Shaw, Holger Siebert, Hengdong Xi, Haitao Xu, Eberhard Bodenschatz
Data Supporting The Paper "Turbulence Induced Cloud Voids: Observation And Interpretation", Katarzyna Karpinska, Jonathan F. E. Bodenschatz, Szymon P. Malinowski, Jakub L. Nowak, Steffen Risius, Tina Schmeissner, Raymond Shaw, Holger Siebert, Hengdong Xi, Haitao Xu, Eberhard Bodenschatz
Department of Physics Publications
No abstract provided.
Dispersion Aerosol Indirect Effect In Turbulent Clouds: Laboratory Measurements Of Effective Radius, K. K. Chandrakar, Will Cantrell, A. Kostinski, Raymond Shaw
Dispersion Aerosol Indirect Effect In Turbulent Clouds: Laboratory Measurements Of Effective Radius, K. K. Chandrakar, Will Cantrell, A. Kostinski, Raymond Shaw
Department of Physics Publications
Cloud optical properties are determined not only by the number density nd and mean radius ṝ of cloud droplets but also by the shape of the droplet size distribution. The change in cloud optical depth with changing nd, due to the change in distribution shape, is known as the dispersion effect. Droplet relative dispersion is defined as d=σr / ṝ . For the first time, a commonly used effective radius parameterization is tested in a controlled laboratory environment by creating a turbulent cloud. Stochastic condensation growth suggests d independent of nd for a nonprecipitating cloud, …
Organization And Oscillations In Simulated Shallow Convective Clouds, Guy Dagan, Ilan Koren, Alexander Kostinski, Orit Altaratz
Organization And Oscillations In Simulated Shallow Convective Clouds, Guy Dagan, Ilan Koren, Alexander Kostinski, Orit Altaratz
Department of Physics Publications
Physical insights into processes governing temporal organization and evolution of cloud fields are of great importance for climate research. Here using large eddy simulations with a bin microphysics scheme, we show that warm convective cloud fields exhibit oscillations with two distinct periods (~10 and ~90 min, for the case studied here). The shorter period dominates the nonprecipitating phase, and the longer period is related to the precipitating phase. We show that rain processes affect the domain's thermodynamics, hence forcing the field into a low‐frequency recharge‐discharge cycle of developing cloudiness followed by precipitation‐driven depletion. The end result of precipitation is stabilization …
Data Supporting The Paper "Dispersion Aerosol Indirect Effect In Turbulent Clouds: Laboratory Measurements Of Effective Radius", K. K. Chandrakar, Will Cantrell, A. Kostinski, R. A. Shaw
Data Supporting The Paper "Dispersion Aerosol Indirect Effect In Turbulent Clouds: Laboratory Measurements Of Effective Radius", K. K. Chandrakar, Will Cantrell, A. Kostinski, R. A. Shaw
Department of Physics Publications
No abstract provided.
Simulation Data Supporting The Paper "Optical Properties And Radiative Forcing Of Fractal-Like Tar Ball Aggregates From Biomass Burning", Janarjan Bhandari, Swarup China, Giulia Girotto, Barbara Scarnato, Kyle Gorkowski, Allison Aiken, Manvendra Dubey, C. Mazzoleni
Simulation Data Supporting The Paper "Optical Properties And Radiative Forcing Of Fractal-Like Tar Ball Aggregates From Biomass Burning", Janarjan Bhandari, Swarup China, Giulia Girotto, Barbara Scarnato, Kyle Gorkowski, Allison Aiken, Manvendra Dubey, C. Mazzoleni
Department of Physics Publications
Simulations data supporting the paper "Optical properties and radiative forcing of fractal-like tar ball aggregates from biomass burning," to be submitted to the Journal of Quantitative Spectroscopy and Radiative Transfer.
Observation Of A Link Between Energy Dissipation Rate And Oscillation Frequency Of The Large-Scale Circulation In Dry And Moist Rayleigh-Bénard Turbulence, Dennis Niedermeier, Kelken Chang, Will Cantrell, Kamal Kant Chandrakar, David Ciochetto, Raymond Shaw
Observation Of A Link Between Energy Dissipation Rate And Oscillation Frequency Of The Large-Scale Circulation In Dry And Moist Rayleigh-Bénard Turbulence, Dennis Niedermeier, Kelken Chang, Will Cantrell, Kamal Kant Chandrakar, David Ciochetto, Raymond Shaw
Department of Physics Publications
In this study both the small- and large-scale flow properties of turbulent Rayleigh-Bénard convection are investigated. Experiments are carried out using the Π chamber (aspect ratio Γ=2) for Rayleigh number range Ra∼108–109 and Prandtl number Pr≈0.7. Furthermore, experiments are run for dry and wet conditions, i.e., top and bottom surfaces of the chamber are dry and wet, respectively. For wet conditions we further distinguish between conditions with and without the presence of sodium chloride aerosol particles which, if supersaturated conditions are achieved, lead to cloud droplet formation. We therefore refer to these conditions as moist and cloudy, …
On The Detection Of Statistical Heterogeneity In Rain Measurements, A. R. Jameson, Michael L. Larsen, A. Kostinski
On The Detection Of Statistical Heterogeneity In Rain Measurements, A. R. Jameson, Michael L. Larsen, A. Kostinski
Department of Physics Publications
The application of the Wiener–Khintchine theorem for translating a readily measured correlation function into the variance spectrum, important for scale analyses and for scaling transformations of data, requires that the data be wide-sense homogeneous (stationary), that is, that the first and second moments of the probability distribution of the variable are the same at all times (stationarity) or at all locations (homogeneity) over the entire observed domain. This work provides a heuristic method independent of statistical models for evaluating whether a set of data in rain is wide-sense stationary (WSS). The alternative, statistical heterogeneity, requires 1) that there be no …
Scaling Of Drizzle Virga Depth With Cloud Thickness For Marine Stratocumulus Clouds, Fan Yang, Edward P. Luke, Pavlos Kollias, Alexander Kostinski, Andrew M. Vogelmann
Scaling Of Drizzle Virga Depth With Cloud Thickness For Marine Stratocumulus Clouds, Fan Yang, Edward P. Luke, Pavlos Kollias, Alexander Kostinski, Andrew M. Vogelmann
Department of Physics Publications
Drizzle is frequently observed in marine stratocumulus clouds and plays a crucial role in cloud lifetime and the radiation budget. Most drizzling stratocumulus clouds form drizzle virga below cloud base, where subcloud scavenging and evaporative cooling are important. We use unique ground‐based cloud radar observations (1) to examine the statistical properties of drizzle frequency and virga depth and (2) to test a simple analytical relationship derived between drizzle virga thickness (Hv) and cloud thickness (Hc). Observations show that 83% of marine stratocumulus clouds are drizzling although only 31% generate surface precipitation. The analytical expression …
Topological Hybrid Silicon Microlasers, Han Zhao, Pei Mao University Of Pennsylvania, Mohammad H. Teimourpour, Simon Malzard, Ramy El-Ganainy, Henning Schomerus, Liang Feng
Topological Hybrid Silicon Microlasers, Han Zhao, Pei Mao University Of Pennsylvania, Mohammad H. Teimourpour, Simon Malzard, Ramy El-Ganainy, Henning Schomerus, Liang Feng
Department of Physics Publications
Topological physics provides a robust framework for strategically controlling wave confinement and propagation dynamics. However, current implementations have been restricted to the limited design parameter space defined by passive topological structures. Active systems provide a more general framework where different fundamental symmetry paradigms, such as those arising from non-Hermiticity and nonlinear interaction, can generate a new landscape for topological physics and its applications. Here, we bridge this gap and present an experimental investigation of an active topological photonic system, demonstrating a topological hybrid silicon microlaser array respecting the charge-conjugation symmetry. The created new symmetry features favour the lasing of a …
Power-Law Scaling Of Extreme Dynamics Near Higher-Order Exceptional Points, Q. Zhong, Demetrios N. Christodoulides, M. Khajavikhan, K. G. Makris, Ramy El-Ganainy
Power-Law Scaling Of Extreme Dynamics Near Higher-Order Exceptional Points, Q. Zhong, Demetrios N. Christodoulides, M. Khajavikhan, K. G. Makris, Ramy El-Ganainy
Department of Physics Publications
We investigate the extreme dynamics of non-Hermitian systems near higher-order exceptional points in photonic networks constructed using the bosonic algebra method. We show that strong power oscillations for certain initial conditions can occur as a result of the peculiar eigenspace geometry and its dimensionality collapse near these singularities. By using complementary numerical and analytical approaches, we show that, in the parity-time (PT) phase near exceptional points, the logarithm of the maximum optical power amplification scales linearly with the order of the exceptional point. We focus in our discussion on photonic systems, but we note that our results apply to other …
Nonthermal Ice Nucleation Observed At Distorted Contact Lines Of Supercooled Water Drops, Fan Yang, Owen Cruikshank, Weilue He, Alexander Kostinski, Raymond Shaw
Nonthermal Ice Nucleation Observed At Distorted Contact Lines Of Supercooled Water Drops, Fan Yang, Owen Cruikshank, Weilue He, Alexander Kostinski, Raymond Shaw
Department of Physics Publications
Ice nucleation is the crucial step for ice formation in atmospheric clouds and therefore underlies climatologically relevant precipitation and radiative properties. Progress has been made in understanding the roles of temperature, supersaturation, and material properties, but an explanation for the efficient ice nucleation occurring when a particle contacts a supercooled water drop has been elusive for over half a century. Here, we explore ice nucleation initiated at constant temperature and observe that mechanical agitation induces freezing of supercooled water drops at distorted contact lines. Results show that symmetric motion of supercooled water on a vertically oscillating substrate does not freeze, …
Data Supporting The Paper "Influence Of Microphysical Variability On Stochastic Condensation In A Turbulent Laboratory Cloud", N. Desai, K. K. Chandrakar, K. Chang, Will Cantrell, Raymond Shaw
Data Supporting The Paper "Influence Of Microphysical Variability On Stochastic Condensation In A Turbulent Laboratory Cloud", N. Desai, K. K. Chandrakar, K. Chang, Will Cantrell, Raymond Shaw
Department of Physics Publications
No abstract provided.