Search results for "Cloud microphysics"

Microphysical Properties of Ice Crystal Precipitation and Surface-Generated Ice Crystals in a High Alpine Environment in Switzerland

2017

AbstractDuring the Cloud and Aerosol Characterization Experiment (CLACE) 2013 field campaign at the High Altitude Research Station Jungfraujoch, Switzerland, optically thin pure ice clouds and ice crystal precipitation were measured using holographic and other in situ particle instruments. For cloud particles, particle images, positions in space, concentrations, and size distributions were obtained, allowing one to extract size distributions classified by ice crystal habit. Small ice crystals occurring under conditions with a vertically thin cloud layer above and a stratocumulus layer approximately 1 km below exhibit similar properties in size and crystal habits as Antarctic/Arctic diamond …

Holographic Observations of Centimeter-Scale Nonuniformities within Marine Stratocumulus Clouds

2020

Abstract Data collected with a holographic instrument [Holographic Detector for Clouds (HOLODEC)] on board the High-Performance Instrumented Airborne Platform for Environmental Research Gulfstream-V (HIAPER GV) aircraft from marine stratocumulus clouds during the Cloud System Evolution in the Trades (CSET) field project are examined for spatial uniformity. During one flight leg at 1190 m altitude, 1816 consecutive holograms were taken, which were approximately 40 m apart with individual hologram dimensions of 1.16 cm × 0.68 cm × 12.0 cm and with droplet concentrations of up to 500 cm−3. Unlike earlier studies, minimally intrusive data processing (e.g., bypassing calculation of number concen…

Reply to a comment by R. Brown on ‘a numerical model of the cloud‐topped planetary boundary‐layer: Radiation, turbulence and spectral microphysics in…

1997

The impact of overshooting deep convection on local transport and mixing in the tropical upper troposphere/lower stratosphere (UTLS)

2015

Abstract. In this study we examine the simulated downward transport and mixing of stratospheric air into the upper tropical troposphere as observed on a research flight during the SCOUT-O3 campaign in connection to a deep convective system. We use the Advanced Research Weather and Research Forecasting (WRF-ARW) model with a horizontal resolution of 333 m to examine this downward transport. The simulation reproduces the deep convective system, its timing and overshooting altitudes reasonably well compared to radar and aircraft observations. Passive tracers initialised at pre-storm times indicate the downward transport of air from the stratosphere to the upper troposphere as well as upward tr…

The water-soluble fraction of marine aerosol particles measured on the Island of Helgoland, North Sea

1997

A Comprehensive Observational Study of Graupel and Hail Terminal Velocity, Mass Flux, and Kinetic Energy

2018

Abstract This study uses novel approaches to estimate the fall characteristics of hail, covering a size range from about 0.5 to 7 cm, and the drag coefficients of lump and conical graupel. Three-dimensional (3D) volume scans of 60 hailstones of sizes from 2.5 to 6.7 cm were printed in three dimensions using acrylonitrile butadiene styrene (ABS) plastic, and their terminal velocities were measured in the Mainz, Germany, vertical wind tunnel. To simulate lump graupel, 40 of the hailstones were printed with maximum dimensions of about 0.2, 0.3, and 0.5 cm, and their terminal velocities were measured. Conical graupel, whose three dimensions (maximum dimension 0.1–1 cm) were estimated from an an…

Drop Shapes and Axis Ratio Distributions: Comparison between 2D Video Disdrometer and Wind-Tunnel Measurements

2009

Abstract Comparisons of drop shapes between measurements made using 2D video disdrometer (2DVD) and wind-tunnel experiments are presented. Comparisons are made in terms of the mean drop shapes and the axis ratio distributions. Very close agreement of the mean shapes is seen between the two sets of measurements; the same applies to the mean axis ratio versus drop diameter. Also, in both sets of measurements, an increase in the oscillation amplitudes with increasing drop diameter is observed. In the case of the 2DVD, a small increase in the skewness was also detected. Given that the two sets of measurements were conducted in very different conditions, the agreement between the two sets of dat…

A Flux Method for the Numerical Solution of the Stochastic Collection Equation: Extension to Two-Dimensional Particle Distributions

2000

Abstract In the present paper a new method is introduced for the numerical solution of the stochastic collection equation in cloud models dealing with two-dimensional cloud microphysics. The method is based on the assumption that the probability for the collision of two cloud drops only depends on the water mass of each and not on the mass of the aerosol nuclei. With this assumption it is possible to reduce the two-dimensional solution of the stochastic collection equation to a one-dimensional approach. First, the two-dimensional particle spectrum is integrated over the aerosol mass yielding a one-dimensional drop spectrum in the water mass grid. For this intermediate drop distribution the …