Showing papers on "Cloud computing published in 1980"

Microphysics of Clouds and Precipitation

Abstract: Cloud physics has achieved such a voluminous literature over the past few decades that a significant quantitative study of the entire field would prove unwieldy. This book concentrates on one major aspect: cloud microphysics, which involves the processes that lead to the formation of individual cloud and precipitation particles. Common practice has shown that one may distinguish among the following additional major aspects: cloud dynamics, which is concerned with the physics responsible for the macroscopic features of clouds; cloud electricity, which deals with the electrical structure of clouds and the electrification processes of cloud and precipitation particles; and cloud optics and radar meteorology, which describe the effects of electromagnetic waves interacting with clouds and precipitation. Another field intimately related to cloud physics is atmospheric chemistry, which involves the chemical composition of the atmosphere and the life cycle and characteristics of its gaseous and particulate constituents. In view of the natural interdependence of the various aspects of cloud physics, the subject of microphysics cannot be discussed very meaningfully out of context. Therefore, we have found it necessary to touch briefly upon a few simple and basic concepts of cloud dynamics and thermodynamics, and to provide an account of the major characteristics of atmospheric aerosol particles. We have also included a separate chapter on some of the effects of electric fields and charges on the precipitation-forming processes.

A cloud parametrization scheme derived from GATE data for use with a numerical model

Abstract: A cloud parametrization scheme which allows for low, medium, high and convective clouds has been developed from GATE data for use in the Meteorological Office 11-layer tropical model. The problems involved in using synoptic observations to derive methods of predicting clouds are discussed. Only limited success was obtained in relating observed cloud amounts to relative humidity and atmospheric temperature structure. The restrictions imposed on the cloud scheme by the model's resolution and by its inability to produce a perfect simulation are considered. In the light of these difficulties a simple approach was adopted based on the assumption that condensation on the smallest scales is part of a larger-scale condensation regime related to the synoptic scale situation. The scheme has been designed to reproduce the main features of a cloud field by relating the large-scale meteorological features associated with a cloud distribution to model variables. Low, medium and high cloud amounts are determined from a quadratic relationship with relative humidity. Low cloud has also been related to the temperature lapse rate in an attempt to model the persistent areas of sub-tropical stratocumulus occurring under inversions. A relative humidity relationship is inappropriate for convective cloud which has, therefore, been related to the convective mass flux calculated in the convection scheme of the model. The scheme has been reasonably successful in predicting the cloudiness associated with the ITCZ and the NE. and SE. trades. The cloud fields showed a good degree of coherence from day to day and there were no signs of unrealistic feedbacks between radiation, cloud and dynamics.

Vertical mass and energy transports by cumulus clouds in the tropics

Abstract: The formal mathematical representation of the transport of energy by convective clouds and the cloud free environment is compared with a relationship based upon the physical structure of the cloud and environment. The relative role of the cloud mean vertical transport of total static energy is obtained by using the physical formulation of these transports and results of budget calculations for the C-scale triangle of the GATE ship array and from direct measurements of cloud parameters by tethered balloon borne instrumentation. Values for the mass flux of the environment are assumed and yield realistic estimates of fractional active cloud cover. For no large scale subsidence in the cloud free regions, active cloud fraction is found to be near 0.05 and cloud base up- and downdrafts may contribute as much as 80 % of the total budget subgrid scale transport of total static energy. When all upward mass flux must pass through cloud base, the mean cloud transport is on the order of 2 × 105 W m-2. These mean transports demonstrate that a small fractional area of active cumulus cloud is indeed capable of performing the necessary energy transports to meet global budgets.

The Multiple Doppler Radar Workshop, November 1979

Abstract: The findings of the Multiple Doppler Radar Workshop are summarized by a series of six papers. Part I of this series briefly reviews the history of multiple Doppler experimentation, fundamental concepts of Doppler signal theory, and organization and objectives of the Workshop. Invited presentations by dynamicists and cloud physicists are also summarized. Experimental design and procedures (Part II) are shown to be of critical importance. Well-defined and limited experimental objectives are necessary in view of technological limitations. Specified radar scanning procedures that balance temporal and spatial resolution considerations are discussed in detail. Improved siting for suppression of ground clutter as well as scanning procedures to minimize errors at echo boundaries are discussed. The need for accelerated research using numerically simulated proxy data sets is emphasized. New technology to eliminate various sampling limitations is cited as an eventual solution to many current problems in Par...

A mathematical model of a cloud

Abstract: The model under consideration is a pencil of radiation incident on a cloud, and the problem is to determine the reflection and transmitted radiation. Based on the method of ‘principle of invariance’, three mathematical models are constructed. The first is the basic model, which describes the radiation system completely. The second is the flux integral model, in which the integral average intensity is considered. The third is the diffusion model, which gives the most important information about the diffused radiation field.

Propagation of co2-laser radiation in a turbulent cloud medium

Abstract: Given are the results of studying CC>2laser continuous beam self-action in a turbulent cloud medium at regular evaporation of droplet. Theoretical results are compared with the data of model experiments carried out in an aerosol chamber 3200 m in volume with artificial mechanical turbulence using a source of radiation with a power of up to 10 wt. The role of conductive heat extraction and turbulent diffusion of evaporating droplets in the formation of temperature and transmittancy profiles in the area of laser beam propagation is considered. Pulsations of temperature, liquid water content and dielectric constant which occur in the interaction zone due to turbulent mixing are analysed as well as their effect on the intensity fluctuations of the radiation passed through the medium. Some features of self-action are investigated in the presence of C02laser radiation fluctuations, for example, those due to the atmospheric inhomogeneities of refractive index. Up to the present numerous works (see for example, / 1,2 / and references there) hare been carried out on studying C0--laser radiation propagation in water aerosol resulting in cloud medium clearing (holeboring). The authors of these works assume that cloud medium and laser radiation parameters do not fluctuate. However, in a turbulent cloud medium wind velocity V and its other parameters are random functions, and the process of clearing such medium has some peculiarities. In particular, in the turbulent cloud medium being cleared additional fluctuations of its parameters and those of laser radiation (besides the existing ones before their perturbation) as well as changed are the medium mean characteristics / 3-7 /. In the present paper given are theoretical and experimental results on thermal self-action of continuous COg-laser radiation in a turbulent cloud medium. A set of equations describing laser radiation and aerosol interaction at an assumed liquid water content approximation involves equations for laser radiation field E , cloud medium temperature T and liquid water content W :