Abstract: The Griffith-Woodley Technique (GWT) is an approach to estimating precipitation using infrared observations of clouds from geosynchronous satellites. It is examined in three ways: an analysis of the terms in the GWT equations; a case study of infrared imagery portraying convective development over Florida; and the comparison of a simplified equation set and resultant rain map to results using the GWT. The objective is to determine the dominant factors in the calculation of GWT rain estimates. Analysis of a single day's convection over Florida produced a number of significant insights into various terms in the GWT rainfall equations. Due to the definition of clouds by a threshold isotherm the majority of clouds on this day did not go through an idealized life cycle before losing their identity through merger, splitting, etc. As a result, 85% of the clouds had a defined life of 0.5 or 1 h. For these clouds the terms in the GWT which are dependent on cloud life history become essentially constant. The empirically derived ratio of radar echo area to cloud area is given a singular value (0.02) for 43% of the sample, while the rainrate term is 20.7 mmh-1 for 61% of the sample. For 55% of the sampled clouds the temperature weighting term is identically 1.0. Cloud area itself is highly correlated (r=0.88) with GWT computed rain volume. An important, discriminating parameter in the GWT is the temperature defining the coldest 10% cloud area. The analysis further shows that the two dominant parameters in rainfall estimation are the existence of cold cloud and the duration of cloud over a point.

Abstract: Accurate global cloud information is required for many climate studies, particularly for validation of climate model simulations. This paper reviews the cloud climatologies currently available, identifying and attempting to explain the differences between various global cloud assessments. The two types of cloud observations used to construct a cloud climatology, conventional surface observations and satellite-derived observations, are contrasted. Meridional profiles of zonally-averaged total cloud amount and the geographic distribution of total cloud amount from 17 cloud data sets are compared. There is at present no unique and/or agreed global cloud climatology. This review emphasizes the uncertainty and inaccuracies associated with the present knowledge of the global cloud distribution. Cloud climatologies constructed from either surface or satellite cloud observations will not be identical. The range of cloud amount available from current cloud climatologies must be noted by all users of globa...

Abstract: The broad characteristics of the North-west Australian Cloud Band, frequently observed across the Australian continent, are outlined. The cloud in the Band is most frequently first apparent within approximately 5° latitude and 17° longitude of 12DS 100°E, and may extend from there for several thousand kilometres, typically towards the east-south-east. It is found to be most in evidence during the winter months. Various atmospheric features associated with the development of the Cloud Band are discussed.

Abstract: Cloud cover is one of the most important variables affecting the earth radiation budget (ERB) and, ultimately, the global climate. The present investigation is concerned with several aspects of the effects of extended cloudiness, taking into account hourly visible and infrared data from the Geostationary Operational Environmental Satelite (GOES). A methodology called the hybrid bispectral threshold method is developed to extract regional cloud amounts at three levels in the atmosphere, effective cloud-top temperatures, clear-sky temperature and cloud and clear-sky visible reflectance characteristics from GOES data. The diurnal variations are examined in low, middle, high, and total cloudiness determined with this methodology for November 1978. The bulk, broadband radiative properties of the resultant cloud and clear-sky data are estimated to determine the possible effect of the diurnal variability of regional cloudiness on the interpretation of ERB measurements.

Abstract: An attempt is made to relate the reflection from a broken cloud field to that from a plane parallel cloud of the same optical properties by using Monte Carlo simulations for a very simple model of an array of regularly spaced, infinitely long bar clouds. Reflection from the array is represented by an effective cloud fraction, and it is shown that for many cases this may be obtained by treating the cloud elements to be noninteracting azimuthally symmetric reflectors. The effective cloud fraction is a function of solar zenith angle, the aspect ratio of the individual cloud elements, and the normal or zenith cloud fraction of the array. Model computations for reflection from an array of randomly distributed identical cylinders are also presented as an example of a possible application of this technique.

Abstract: The invention relates to a camouflage screen generator which can generate a cloud which is opaque in the visible range and/or in the infrared range, around a mobile vehicle, such as a combat vehicle, and can move with it The generator comprises a tank 10 of products to be dispersed, which products are liquid or powdery and generate a cloud which is opaque in the visible range and/or in the infrared range, and a compressed-gas tank 12, both these being on board the vehicle, the camouflage cloud being emitted by a plurality of nozzles 16 distributed along the periphery of the vehicle and connected to the tank of products via pipework

Abstract: The economical importance of the winter snowpack to the Colorado Rocky Mountain region (e.g., weather modification potential, ski industry, avalanche prediction, snow removal, etc.) calls for an understanding of how the mountain environment and synoptic weather systems interact to produce precipitating orographic cloud systems. This may be achieved by recognizing that each cloud system can be broken down into individual cloud components. In each of the case studies, a synoptic cloud component, an orographic cloud component and a convective cloud component were identified through the analysis of rawinsonde data, vertically pointing radar data, and visual observations. This study shows that wintertime cloud systems over mountainous terrain can be thought of as being composed of cloud components that form when vertical velocity components act on different size and time scales (synoptic, orographic, convective). The following atmospheric phenomena are shown to be important factors which contribute to...

Abstract: Improvements made to the cloud removal method for landsat MSS images proposed by O.R. Mitchell are presented. A more reasonable mathematical model for the cloud effect has been derived, and a two-stage filtering scheme based on this new model has been proposed. A filtering and a 3-D processing method for landsat MSS image noise cleaning has been developed to implement the scheme. A preliminary experiment shows promising results.

Abstract: The World Climate Research Programme (WCRP) plan is concerned with the need to develop a uniform global cloud climatology as part of a broad research program on climate processes. The International Satellite Cloud Climatology Project (ISCCP) has been approved as the first project of the WCRP. The ISCCP has the basic objective to collect and analyze satellite radiance data to infer the global distribution of cloud radiative properties in order to improve the modeling of cloud effects on climate. Research is conducted to explore an algorithm for retrieving cloud properties by utilizing the available infrared sounder data from polar-orbiting satellites. A numerical method is developed for computing cloud top heights, amount, and emissivity on the basis of a parameterized infrared radiative transfer equation for cloudy atmospheres. Theoretical studies were carried out by considering a synthetic atmosphere.

Abstract: Summary studies are presented for the entire cloud observation archieve from the NASA Global Atmospheric Sampling Program (GASP). Studies are also presented for GASP particle concentration data gathered concurrently with the cloud observations. Cloud encounters are shown on about 15 percent of the data samples overall, but the probability of cloud encounter is shown to vary significantly with altitude, latitude, and distance from the tropopause. Several meteorological circulation features are apparent in the latitudinal distribution of cloud cover, and the cloud encounter statistics are shown to be consistent with the classical mid-latitude cyclone model. Observations of clouds spaced more closely than 90 minutes are shown to be statistically dependent. The statistics for cloud and particle encounter are utilized to estimate the frequency of cloud encounter on long range airline routes, and to assess the probability and extent of laminar flow loss due to cloud or particle encounter by aircraft utilizing laminar flow control (LFC). It is shown that the probability of extended cloud encounter is too low, of itself, to make LFC impractical.

Abstract: Summary studies are presented for the entire cloud observation archive from the NASA Global Atmospheric Sampling Program (GASP). Studies are also presented for GASP particle-concentration data gathered concurrently with the cloud observations. Cloud encounters are shown on about 15 percent of the data samples overall, but the probability of cloud encounter is shown to vary significantly with altitude, latitude, and distance from the tropopause. Several meteorological circulation features are apparent in the latitudinal distribution of cloud cover, and the cloud-encounter statistics are shown to be consistent with the classical mid-latitude cyclone model. Observations of clouds spaced more closely than 90 minutes are shown to be statistically dependent. The statistics for cloud and particle encounter are utilized to estimate the frequency of cloud encounter on long-range airline routes, and to assess the probability and extent of laminaar flow loss due to cloud or particle encounter by aircraft utilizing laminar flow control (LFC). It is shown that the probability of extended cloud encounter is too low, of itself, to make LFC impractical. This report is presented in two volumes. Volume I contains the narrative, analysis, and conclusions. Volume II contains five supporting appendixes.

Abstract: Etude de l'extinction interstellaire par la methode des comptages d'etoiles. L'analyse revele la presence de deux grands complexes de nuages sombres associes aux bras spiraux

Abstract: When applying any of the methods for calculating the radiation regime and its variability for cumulus clouds, in addition to the optical characteristics of an individual cloud it is important to know something about the size distribution of the clouds and the structure of the cloud field.

Abstract: : In response to Air Weather Service requirements, the Air Force Geophysics Lab has been involved in research in the development of mesoscale advection fog prediction techniques. A two-dimensional fog prediction model developed at the Naval Environmental Prediction Research Facility (NEPRF) was selected for evaluation because it can operate on a mini-computer of the size planned for the Air Force's Automated Weather Distribution System (AWDS). Six case studies developed by Calspan Advanced Technology Center were used to test the model's accuracy. These case studies covered a wide range of fog/stratus formation and dissipation stages. Four major weaknesses were identified in the model. The most important was that cloud tops increased in temperature through infrared radiative heat processes rather than decreased. The other weaknesses include lack of solar radiation processes, unreliable treatment of the height of mixed layer during stable conditions, and insufficient handling of vertical motions. The model may have potential in AWDS. However, these weaknesses must first be corrected.

Abstract: A one-dimensional radiative transfer scheme is presented which accounts for the effects of broken cloud in the solar and infrared radiation field The fractional cloud amount is explicitly considered in the two-stream model by treating clouds as the boundary condition between two adjacent atmospheric layers The scheme accounts for absorption and scattering by gases and aerosols assuming realistic atmospheres The radiative properties of broken clouds are included in a parameterized form making use of results from three-dimensional radiative transfer models The radiative characteristics of a cloud field are represented by an average finite cloud whose size or optical thickness grows with increasing cloud amount This growth is described by a simple mathematical model, and its use yields qualitative agreement between model results and observations for solar radiation The scheme is then applied to calculate the net radiative effect of broken cloud Since the cloud size growth with cloud amount implies a non-linear relation between the fractional cloud amount and the radiative properties of the cloud field, the net radiative effect of cloud depends on cloud amount The idealized model shows that the albedo effect (increase of solar reflection with cloud amount) of broken cloud is smaller than that of a plane-parallel cloud for cloud amounts less than about 07, while the opposite is true for larger cloud amounts The greenhouse effect (reduction of the outgoing long-wave flux) of broken cloud is larger than that of a plane-parallel cloud for small cloud amount and smaller for large cloud amount An application of the radiation scheme to compute bispectral curves of visible albedo versus thermal brightness temperature shows that broken cloud layers and unbroken layers with variable optical depths show a similar shape of the bispectral curve DOI: 101111/j1600-08701984tb00259x

Abstract: Abstract Interstellar extinction within 4 kpc from the sun is investigated in the field of 351° ≤ l ≤ 1 ° through l = 0° and |b| ≤ 2° by means of the star-count method on the basis of the observed cumulative number and a space distribution model of late M giants. The general interstellar extinction in visual wavelengths is about 2.5 mag kpc–1 in the galactic plane and the scale height is about 100 pc in a distance range from 1.5 to 4 kpc from the sun for the distance, 10 kpc, of the sun from the galactic center. The space distribution analysis reveals two large dark cloud complexes associated with the spiral arms: one is around l = 352° and 2 kpc from the sun, and the other is around l = 359° and 3.2 kpc from the sun. The size of the complexes is about 300 pc in the direction of the galactic longitude, and the complexes may consist of many dark clouds.