Artificial Cloud Research Articles

Radiative Heating of High‐Level Clouds and Its Impacts on Climate

AbstractThe interactions of clouds with radiation influence climate. Many of these impacts appear to be related to the radiative heating and cooling from high‐level clouds, but few studies have explicitly tested this. Here, we use simulations with the ICON‐ESM model to understand how high‐level clouds, through their radiative heating and cooling, influence the large‐scale atmospheric circulation and precipitation in the present‐day climate. We introduce a new method to diagnose the radiative heating of high‐level clouds: instead of defining high‐level clouds as all clouds at temperatures colder than −35°C, we define them as all clouds with a cloud top at temperatures colder than −35°C. The inclusion of the lower cloud parts at temperatures warmer than −35°C circumvents the creation of artificial cloud boundaries and strong artificial radiative heating at the temperature threshold. To isolate the impact of high‐level clouds, we analyze simulations with active cloud‐radiative heating, with the radiative heating from high‐level clouds set to zero, and with the radiative heating from all clouds set to zero. We show that the radiative interactions of high‐level clouds warm the troposphere and strengthen the eddy‐driven jet streams, but have no impact on the Hadley circulation strength and the latitude of the Intertropical Convergence Zone. Consistent with their positive radiative heating and energetic arguments, high‐level clouds reduce precipitation throughout the tropics and lower midlatitudes. Overall, our results confirm that the radiative interactions of high‐level clouds have important impacts on climate and highlight the need for better representing their radiative interactions in models.

Microwave Diagnostics of Electrical Discharges in an Artificial Cloud of Charged Water Drops

Microwave Diagnostics of Electrical Discharges in an Artificial Cloud of Charged Water Drops

Droplets size characterization for cold water clouds by means of Generalised Scattering Imaging

This paper describes an experimental investigation carried out at the Italian Aerospace Research Centre (CIRA) laboratory for the application of the Generalized Scattering Imaging (GSI) technique. The droplets were generated by a monodisperse droplet generator and a multi-disperse conical nozzle. This latter is currently used for making the artificial cloud in the CIRA Icing Wind Tunnel (IWT). The measurements are devoted to assessing the application of GSI for the characterization of the cold cloud of CIRA-IWT. The experiments were conducted considering two camera models and demanding technical solutions for the illumination and layout constraints faced for the future implementation of GSI in IWT. To reduce into a linear pattern the enlarged defocused interference fringes, it is found that the optimal aperture of the slit is 5 mm. For the monodisperse droplet distribution, the results show discrepancies between the predicted and the measured diameters regardless of the sharp distribution of the occurrences of the droplet diameters. However, the dispersion found for the droplets generated by the conical nozzle exhibits the expected large variability. This effect is more emphasized when the imaged region is discretized in sub-windows, the number of droplets in each dramatically decreases, however compromising the results of the statistics. Different camera models and imaging configurations led to a variety of measurements at different spatial resolutions.

Comprehensive Efficiency Evaluation of Aircraft Artificial Cloud Seeding in Hunan Province, China, Based on Numerical Simulation Catalytic Method

Aircraft cloud seeding refers to the use of equipment on aircraft to release chemicals into clouds, changing their physical and chemical properties to increase rainfall or snowfall. The purpose of precipitation enhancement is to alleviate drought and water scarcity issues. Due to the complexity of the technology, the precise control of factors such as cloud characteristics and chemical release amounts is necessary. Therefore, a scientific evaluation of the potential of aircraft cloud seeding can help to improve the effectiveness of the process, and is currently a technical challenge in weather modification. This study used the mesoscale numerical model WRF coupled with a catalytic process to simulate and evaluate the seven aircraft cloud seeding operations conducted in Hunan Province in 2021. The results show that WRF can effectively evaluate the effectiveness of cloud seeding. When the water vapor conditions are suitable, the airborne dispersion of silver iodide (AgI) can significantly increase the content of large particles of high-altitude ice crystals, snow, and graupel, resulting in an increase in low-level rainwater content and, correspondingly, an increase in ground precipitation. When the water vapor conditions are insufficient, the dispersion of AgI does not trigger effective precipitation, consistent with the results of station observations and actual flight evaluations. This study provides an effective method for scientifically evaluating the potential and effectiveness of aircraft cloud seeding operations.

Artificial atmospheric cloud formations: state and prospects of research

The article presents a classification of atmospheric cloud formations, which includes, along with clouds and fogs of natural origin, also anthropogenic atmospheric cloud formations of an unintentional nature, accompanying human economic activity, and intentional nature (artificial clouds and fogs purposefully created by man).
 Based on a systematic analysis of patent materials and information sources in this subject area, possible methods for creating artificial clouds and fogs are summarized, indicating the level of their implementation.
 It is shown that at present it is possible to create the following types of artificial clouds and fogs: artificial cirrus crystalline clouds, artificial convective clouds, artificial wavy clouds, artificial fogs, artificial low-altitude water-aerosol formations. Some results of field experiments on the creation of artificial fogs and clouds of various forms in our country and abroad are presented. 
 The list of solved applied tasks in the creation of artificial clouds and fogs is defined. The possibility of solving such problems is shown by the example of destroying thunderstorms, hail in large areas with the help of artificial cirrus clouds and by the example of destroying frost with the help of artificial fogs created by thermo kinetic installations.

Nonlinear Three-Dimensional Simulations of the Gradient Drift and Secondary Kelvin–Helmholtz Instabilities in Ionospheric Plasma Clouds

A newly developed three-dimensional electrostatic fluid model solving continuity and current closure equations aims to study phenomena that generate ionospheric turbulence. The model is spatially discretized using a pseudo-spectral method with full Fourier basis functions and evolved in time using a four-stage, fourth-order Runge Kutta method. The 3D numerical model is used here to investigate the behavior and evolution of ionospheric plasma clouds. This problem has historically been used to study the processes governing the evolution of the irregularities in the F region of the ionosphere. It has been shown that these artificial clouds can become unstable and structure rapidly (i.e., cascade to smaller scales transverse to the ambient magnetic field). The primary mechanism which causes this structuring of ionospheric clouds is the E×B, or the gradient drift instability (GDI). The persistence and scale sizes of the resulting structures cannot be fully explained by a two-dimensional model. Therefore, we suggest here that the inclusion of three-dimensional effects is key to a successful interpretation of mid-latitude irregularities, as well as a prerequisite for a credible simulation of these processes. We investigate the results of 2D and 3D nonlinear simulations of the GDI and secondary Kelvin–Helmholtz instability (KHI) in plasma clouds for three different regimes: highly collisional (≈200 km), collisional (≈300 km), and inertial (≈450 km). The inclusion of inertial effects permits the growth of the secondary KHI. For the three different regimes, the overall evolution of structuring of plasma cloud occurs on longer timescales in 3D simulations. The inclusion of three-dimensional effects, in particular, the ambipolar potential in the current closure equation, introduces an azimuthal “twist“ about the axis of the cloud (i.e., the magnetic field B). This azimuthal “twist” is observed in the purely collisional regime, and it causes the perturbations to have a non-flute-like character (k‖≠0). However, for the 3D inertial simulations, the cloud rapidly diffuses to a state in which the sheared azimuthal flow is substantially reduced; subsequently, the cloud becomes unstable and structures, by retaining the flute-like character of the perturbations (k‖=0).

Rocket‐Released Neutral Clouds in the Ionosphere: Formation, Evolution, and Detection

AbstractReleasing diffuse artificial clouds into the space environment using a rocket or spacecraft can modify the natural plasma state. This uses space itself as a laboratory for studying plasma phenomena that cannot be reproduced on the ground. The Space Measurement of A Rocket‐released Turbulence (SMART) mission will inject a beam of barium neutral vapor into the ionosphere and perpendicular to the Earth's magnetic field. Barium atoms will be photoionized, forming an ion ring distribution that is unstable to lower hybrid waves. Large amplitude lower hybrid waves nonlinearly scatter to whistler and magnetosonic waves that can propagate out to the magnetosphere. This paper details the theory, modeling, and simulation we used to design this release experiment to optimize the energy in the plasma waves under a variety of constraints. A product of this analysis is quantitative predictions for some in situ and remote measurements. Hydrocode simulations of barium vapourization and acceleration via shaped charge provide the initial state of the neutral beam. We optimize the apogee, orientation, and position of the payload and instruments. Cloud dynamics are simulated with a direct simulation Monte Carlo technique, which includes photoionization with metastable barium states, collisions with the neutral background atmosphere, optical line emission, gravity, and electromagnetic forces. We predict the plasma density measured by the instrument payload and the remotely measured optical intensity. We also examine how the plasma wave growth differs at the measurement location compared to the bulk of the barium cloud.

Effects of pH and light exposure on the survival of bacteria and their ability to biodegrade organic compounds in clouds: implications for microbial activity in acidic cloud water

Abstract. Recent studies have reported that interactions between live bacteria and organic matter can potentially affect the carbon budget in clouds, which has important atmospheric and climate implications. However, bacteria in clouds are subject to a variety of atmospheric stressors, which can adversely affect their survival and energetic metabolism and, consequently, their ability to biodegrade organic compounds. At present, the effects of cloud water pH and solar radiation on bacteria are not well understood. In this study, we investigated how cloud water pH (pH 3 to 6) and exposure to solar radiation impact the survival and energetic metabolism of two Enterobacter bacterial strains that were isolated from ambient air collected in Hong Kong and their ability to biodegrade organic acids. Experiments were conducted using simulated sunlight (wavelength from 320 to 700 nm) and microcosms comprised of artificial cloud water that mimicked the pH and chemical composition of cloud water in Hong Kong, South China. Our results showed that the energetic metabolism and survival of both strains depended on the pH. Low survival rates were observed for both strains at pH<4, regardless of whether the strains were exposed to simulated sunlight. At pH 4 to 5, the energetic metabolism and survival of both strains were negatively impacted only when they were exposed to simulated sunlight. Organic compounds such as lipids and peptides were detected during exposure to simulated sunlight at pH 4 to 5. In contrast, there were minimal effects on the energetic metabolism and the survival of both strains when they were exposed to simulated sunlight at pH>5. The biodegradation of organic acids was found to depend on the presence (or absence) of simulated sunlight and the pH of the artificial cloud water medium. Overall, this study provides new insights into how two common atmospheric stressors, cloud water pH and exposure to solar radiation, can influence the survival and energetic metabolism of bacteria, and consequently the roles that they play in cloud processes.

Results of Field Experiments for the Creation of Artificial Updrafts and Clouds

This study documents results from a series of field experiments on the creation of artificial updrafts and convective clouds at a test site in the United Arab Emirates (UAE). The proposed method incorporates a vertically directed jet from an aircraft turbojet engine saturated with active hygroscopic aerosols for the purpose of energetically feeding the jet with water vapor condensation heat below cloud base level. This paper presents the description and main characteristics of the experimental equipment, methodology of experiments and atmospheric conditions, analysis of the obtained results, and prospects for further development of the proposed method. On the whole, the experiments showed that under the conditions of low air humidity, typical for the UAE, and the slowness of the condensation process, the replenishment of the jet energy by the heat of condensation is too small, and the power of the used jet engine in the experiments is insufficient to overcome surface temperature inversions, horizontal winds, and initiation of deep convection. Nevertheless, the results of field experiments and numerical simulation made it possible to outline promising directions for further research on improving the considered method for creating artificial clouds and precipitation.

Emerging investigator series: aqueous photooxidation of live bacteria with hydroxyl radicals under cloud-like conditions: insights into the production and transformation of biological and organic matter originating from bioaerosols.

Live bacteria in clouds are exposed to free radicals such as the hydroxyl radical (˙OH), which is the main driver of many photochemical processes. While the ˙OH photooxidation of organic matter in clouds has been widely studied, equivalent investigations on the ˙OH photooxidation of bioaerosols are limited. Little is known about the daytime encounters between ˙OH and live bacteria in clouds. Here we investigated the aqueous ˙OH photooxidation of four bacterial strains, B. subtilis, P. putida, E. hormaechei B0910, and E. hormaechei pf0910, in microcosms composed of artificial cloud water that mimicked the chemical composition of cloud water in Hong Kong. The survival rates for the four bacterial strains decreased to zero within 6 hours during exposure to 1 × 10-16 M of ˙OH under artificial sunlight. Bacterial cell damage and lysis released biological and organic compounds, which were subsequently oxidized by ˙OH. The molecular weights of some of these biological and organic compounds were >50 kDa. The O/C, H/C, and N/C ratios increased at the initial onset of photooxidation. As the photooxidation progressed, there were few changes in the H/C and N/C, whereas the O/C continued to increase for hours after all the bacterial cells had died. The increase in the O/C was due to functionalization and fragmentation reactions, which increased the O content and decreased the C content, respectively. In particular, fragmentation reactions played key roles in transforming biological and organic compounds. Fragmentation reactions cleaved the C-C bonds of carbon backbones of higher molecular weight proteinaceous-like matter to form a variety of lower molecular weight compounds, including HULIS of molecular weight <3 kDa and highly oxygenated organic compounds of molecular weight <1.2 kDa. Overall, our results provided new insights at the process level into how daytime reactive interactions between live bacteria and ˙OH in clouds contribute to the formation and transformation of organic matter.

Study of the Possibility of Stimulating Cloud Convection by Solar Radiation Energy Absorbed in an Artificial Aerosol Layer

We consider the possibility of creating artificial clouds similar to Pyro clouds formed in nature over large forest and other fires. It is assumed that the creation of an artificial surface aerosol layer that absorbs solar radiation can lead to the heating of local air volumes and initiate thermal convection. The possibility of such convection was examined theoretically using the computational fluid dynamics software package suite FlowVision, in which the equations of motion, energy and mass transfer are solved in relative variables. Numerical experiments showed the principal possibility of initiating cloud convection only under some favorable atmospheric conditions (low wind speeds, temperature lapse rate greater than 8–9 °C/km), with an aerosol layer area of at least 5–10 km2 and a duration of its existence (heating) of at least 30 min. To assess the possibility of the practical implementation of this method, eight variants of highly efficient smoke compositions were developed and tested, and two batches of aerosol checkers weighing 25 kg, creating an aerosol of optimal size to absorb solar radiation, were produced. Calculations of the required dose based on the results of laboratory and field tests of the checkers showed that for one experiment to initiate cloud convection several thousand checkers need to be burned. The consumption of pyrotechnic aerosol composition (tens of tons) is about 1.5 times less than the burning of petroleum products in previously tested meteotrons. However, for environmental safety purposes, full-scale tests and the application of the aerosol layer method is advisable to conduct away from populated areas.

Unusual Plasma Formations Produced by Positive Streamers Entering the Cloud of Negatively Charged Water Droplets

AbstractKostinskiy et al. (2015b), https://doi.org/10.1002/2015GL065620, using a high‐speed infrared (2.5–5.5 μm) camera, discovered the so‐called unusual plasma formations (UPFs) in artificial clouds of charged water droplets. UPFs had complex morphology including both streamer‐like regions and hot channel segments. They were observed both in the presence and in the absence of hot leader channels developing from the grounded plane toward the cloud. In this paper, which is aimed at revealing the genesis of UPFs, we present two UPFs that occurred inside the initial corona streamer burst of positive polarity emitted from the grounded plane, prior to the formation (or in the absence) of associated hot leader channel. These streamer bursts developed at speeds of 5–7 × 105 m/s over 1–1.5 m before entering the optically visible negatively charged cloud and producing UPFs at its periphery. Hot channel segments within UPFs were formed in very short times of the order of 1 μs or less. It is not clear if the UPFs were caused solely by the enhanced electric field near the charged cloud boundary or other factors also played a role. Occurrence of UPFs may be a necessary component of the lightning initiation process.

Atmospheric conditions favorable for the creation of artificial clouds by a jet saturated with hygroscopic aerosol

The possibility of creating artificial clouds based on theoretical modeling of a vertically directed buoyancy jet was analyzed considering vertical temperature lapse rate, wind speed, relative humidity of the near-ground atmospheric layer, and thickness of the inversion layer. Numerical experiments demonstrated that a jet with an initial velocity of 300 m/s, the temperature of 300 °C, and flow volume of 240 m3/s without additional energy feeding can reach the condensation level in certain conditions, namely, absence of an inversion layer, vertical temperature lapse rate >8 °C/km, and humidity >85%. The introduction of three types of hygroscopic aerosols with different hygroscopic points into the jet and the replenishment of the jet energy with heat from the condensation of water vapor can expand the boundaries of favorable conditions for stimulating thermal convection and creating artificial clouds. The results can be used to develop criteria for choosing days with favorable conditions for conducting field experiments.

CFD simulation of updrafts initiated by a vertically directed jet fed by the heat of water vapor condensation

This paper presents the results of the development of a mathematical model and numerical simulation of the ascent in the atmosphere of a vertically directed jet fed by the heat of condensation of water vapor on a hygroscopic aerosol introduced into the jet at the start. The possibility of creating artificial convective clouds depending on jet parameters, condensation heat value and vertical profiles of wind speed, air temperature and humidity has been evaluated. Numerical experiments showed that the motion of a high-speed and high-temperature jet in the atmosphere has a complex turbulent nature. As the jet ascends, it expands, losing superheat and velocity. The temperature of the jet decreases faster than the velocity, so the jet rises slightly above the level at which its superheat disappears. The jet's ascent height increases as the humidity of the air and the vertical temperature gradient increase. Wind causes the jet to deform, bend, and decrease the height of ascent. Feed the jet with condensation heat results in a significant increase in jet lift height. This is particularly effective in the case of introducing into the jet two-layer NaCl/TiO2 nanoaerosol, which is capable of absorbing water vapor in an amount significantly greater than its mass. The simulation results are encouraging in the possibility of creating artificial updrafts that can lead to the formation of convective clouds and precipitation on days with favorable atmospheric conditions, when wind speed in the sub-cloud layer is < 6 m/s, air humidity is > 65%, and the temperature lapse rate is > 7.5 °C/km.

LARGE-SCALE ONLINE LEARNING SUPPORTED BY INTELLIGENT DEVICES IN THE POST-PANDEMIC ERA

With the support of emerging technologies such as artificial intelligence and cloud computing, China began learning and teaching online in 2020 to control the spread of the pandemic and implement the "Classes are suspended, but learning continues" policy. Online learning and teaching require modified methods, management, and evaluation compared with traditional instruction. Moreover, teachers' and students' thinking styles and ways of communication have also changed in terms of practice, places of study and tasks. The large-scale online teaching-learning model has ushered in new teaching and learning reform trends in the post-pandemic era. Therefore, this study investigates students' and teachers' readiness for, acceptance of, and satisfaction about comprehensive online teaching and learning and explores the effect online learning has on students. To achieve the research aim, 67 students from one city and one village in China were surveyed.The results revealed that online teaching was met with medium levels of readiness and acceptance and gave little satisfaction. For students, attitudes toward learning, support (or lack thereof) from instructors, effective interactions, motivation to learn, and self-regulation influenced online learning satisfaction. In addition, the students' grade levels and locations.

A point cloud registration method based on dual quaternion description with point-linear feature constraints

ABSTRACT Point cloud registration refers to a critical step in point cloud preprocessing, which aims to uniformly represent the objects expressed by the two point sets. To solve spatial discrepancies in the collected artificial building point clouds, this study develops a point cloud registration method by employing dual quaternion description based on the point-linear feature constraint. First, the spatial transformation parameters are expressed by the dual quaternion, and the rotation matrix and translation vector are expressed simultaneously to avoid the error of separate calculations from accumulating. Subsequently, the registration model is built by complying with the constraints of coordinate equivalence after the registration of the same-name points, parallelism of direction vectors after registration of the same-name lines and the spatial geometric relationship between points and lines. On that basis, the scale factor is considered to register point clouds at different scales. Second, an optimized Levenberg–Marquardt method is adopted to solve the registration model for avoiding the iterative non-convergence attributed to inappropriate initial values in the solution. Lastly, the robustness and reliability exhibited by the proposed method are verified by performing two experiments with the simulated and measured data. As indicated from the experimentally achieved results, the joint constraint of point-linear features can achieve higher accuracy than the constraint of point or line features independently, and the combined point-linear features can register point clouds in high quality when point cloud data are scaled and partially missing. This study presents an effective registration method for manually registered auxiliary targets when they are difficult to deploy.

Managing customer satisfaction: digital applications for insurance companies

Customer satisfaction management is increasing in importance within the insurance industry. In particular, to define a customer-oriented strategy, installing digital applications based on technologies, e.g. including artificial intelligence or cloud computing, ranks among the major strategic challenges. Against this background, the aim of this paper is to take an integrated perspective on managing customer satisfaction and the digital transformation. Towards this end, we identify and assess a set of digital applications, as a result of a comprehensive review of 106 academic papers and publications of the industry and supervisory authorities. We illustrate the opportunities to increase customer satisfaction and emphasise their impact on insurers at four major customer touch points: contract conclusion, contract modifications, the event of damage and further contacts. Our results are strategic measures to strengthen the position for sales and marketing, to simplify standard processes and to increase efficiency and interaction with the customer.

Microwave diagnostics of electrical discharges in an artificial cloud of charged water drops

The microwave diagnostics of discharges occurring in an artificial cloud of charged water droplets created in an open air simulating the environment of thunderclouds is implemented. An artificial cloud with a droplet size of about 1 microns is opaque in the visible range, so intra-cloud discharges are not available for investigation by traditional methods in the spark discharge physics based on the registration of visible discharge radiation. Microwaves pass through such a cloud without noticeable attenuation, they interact only with the plasma of discharges occurring in the cloud. The probing microwave radiation had a wavelength of 8 mm. The attenuation of microwaves passed through the cloud was measured with temporary resolution of about 10 ns. The temporal characteristics of intra-cloud discharges were investigated. Keywords: spark, leader, streamer, electromagnetic wave.

Микроволновая диагностика разрядов в искусственном облаке заряженных водяных капель

The microwave diagnostics of discharges occurring in an artificial cloud of charged water droplets created in an open air simulating the environment of thunderclouds is implemented. An artificial cloud with a droplet size of about 1 microns is opaque in the visible range, so intra-cloud discharges are not available for investigation by traditional methods in the spark discharge physics based on the registration of visible discharge radiation. Microwaves pass through such a cloud without noticeable attenuation, they interact only with the plasma of discharges occurring in the cloud. The probing microwave radiation had a wavelength of 8 mm. The attenuation of microwaves passed through the cloud was measured with temporary resolution of about 10 ns. The temporal characteristics of intra-cloud discharges were investigated.

Tracking Cloud Forests With Cloud Technology and Random Forests

Hotspots of endemic biodiversity, tropical cloud forests teem with ecosystem services such as drinking water, food, building materials, and carbon sequestration. Unfortunately, already threatened by climate change, the cloud forests in our study area are being further endangered during the Covid pandemic. These forests in northern Ecuador are being razed by city dwellers building country homes to escape the Covid virus, as well as by illegal miners desperate for money. Between August 2019 and July 2021, our study area of 52 square kilometers lost 1.17% of its tree cover. We base this estimate on simulations from the predictive model we built using Artificial Intelligence, satellite images, and cloud technology. When simulating tree cover, this model achieved an accuracy between 96 and 100 percent. To train the model, we developed a visual and interactive application to rapidly annotate satellite image pixels with land use and land cover classes. We codified our algorithms in an R package—loRax—that researchers, environmental organizations, and governmental agencies can readily deploy to monitor forest loss all over the world.