Positive cloud-to-ground flashes

Top PDF Positive cloud-to-ground flashes:

The Characterization Of Negative Cloud-To-Ground Lightning Flashes In Malaysia Under The Influence Of Pollution

The Characterization Of Negative Cloud-To-Ground Lightning Flashes In Malaysia Under The Influence Of Pollution

The first process in the generation of lightning is charge separation [14]. There are two hypotheses describing the process: Polarization mechanism hypothesis and electrostatic induction hypothesis. For polarization mechanism hypothesis by which charge separation occur still be the subject for researchers and this hypothesis has two components. Firstly, falling droplets of ice and rain become electrically polarized as they fall through the atmosphere's natural electric field. Secondly, colliding ice particles become charged by electrostatic induction. Ice and super-cooled water are the keys to the process. Violent winds buffet tiny hailstones as they form, causing them to collide. When the hailstones hit ice crystals, some negative ions transfer from one particle to another. The smaller, lighter particles lose negative ions and become positive; the larger, more massive particles gain negative ions and become negative.
Show more

24 Read more

Cloud-to-ground lightning and surface rainfall in warm-season Florida thunderstorms

Cloud-to-ground lightning and surface rainfall in warm-season Florida thunderstorms

[ 1 ] Relationships between cloud-to-ground (CG) lightning and surface rainfall have been examined in nine isolated, warm-season thunderstorms on the east coast of central Florida. CG flashes and the associated rain volumes were measured as a function of time in storm-centered reference frames that followed each storm over a network of rain gauges. Values of the storm-average rain volume per CG flash ranged from 0.70  10 4 to 6.4  10 4 m 3 /CG flash, with a mean (and standard deviation) of 2.6  10 4 ± 2.1  10 4 m 3 /CG flash. Values of the rain volume concurrent with CG flashes ranged from 0.11  10 4 to 4.9  10 4 m 3 /CG flash with a mean of 2.1  10 4 ± 2.0  10 4 m 3 /CG flash. The lag-time between the peak CG flash rate and the peak rainfall rate (using 5 min bins), and the results of a lag correlation analysis, show that surface rainfall tends to follow the lightning (positive lag) by up to 20 min in six storms. In one storm the rainfall preceded the lightning by 5 min, and two storms had nonsignificant lags. Values of the lagged rain volume concurrent with CG flashes ranged from 0.43  10 4 to 4.9  10 4 m 3 /CG flash, and the mean was 1.9  10 4 ± 1.7  10 4 m 3 /CG flash. For the five storms that produced 12 or more flashes and had significant lags, a plot of the optimum lag time versus the total number of CG flashes shows a linear trend (R 2 = 0.56). The number of storms is limited, but the lag results do indicate that large storms tend to have longer lags. A linear fit to the lagged rain volume vs. the number of concurrent CG flashes has a slope of 1.9  10 4 m 3 /CG flash (R 2 = 0.83). We conclude that warm-season Florida
Show more

15 Read more

Narrow Band Field Measurement Generated By Lightning Flashes

Narrow Band Field Measurement Generated By Lightning Flashes

When the lightning is near to the ground which contains positive ions, the negative ions from the cloud will be attract to the positive ions on the ground. The positive ion from the ground will cause the upward moving discharge from the ground to the cloud. This process is called the return stroke and the flash can be up 26 strokes but in average are only three to five strokes. This return stroke has very high emission radiation based on the previous experiment. In this return stroke there was fast front and also slow front that only happen in very short time. This to parameter is very important to know the effect of the return stroke to the equipment that is very sensitive.
Show more

24 Read more

Point Cloud Generation for Ground Surface Modeling Employing MAV in Outdoor Environment

Point Cloud Generation for Ground Surface Modeling Employing MAV in Outdoor Environment

Ground surface modeling has become an im- portant research area during the past few years. While computer vision approach suffers from some inherent problems like lighting condition dependency, we propose a Micro Aerial Vehi- cle (MAV) equipped with Global Positioning System (GPS), barometer, Inertial Measurement Unit (IMU) and laser scanner as an alternative solution for generating ground surface models. We suggest a first method which make use of all those sensors except the laser scanner and a second method incorporating this laser scanner with a scan matching algorithm. We evaluate those two methods by generating point cloud in each case. We also devise and apply a simple yet useful algorithm called BacktransformLaser- Scan that is useful to evaluate the feasibility of any laser scan matching algorithm to certain ap- plication, hence, show its usefulness.
Show more

9 Read more

The Cloud-to-Ground Lightning Parameterization Development with the Canadian Local Climate Model

The Cloud-to-Ground Lightning Parameterization Development with the Canadian Local Climate Model

include radiation, hydrology, the convection, topography, the boundary layer and the surface heat flows. These parameters are recalculated from the global climate model (MGC) routines for each time step of the model (20 minutes). This model uses the Canadian Land Surfaces Scheme (CLASS) [70,71] to illustrate the vegetation influence on the surface energy budget. CLASS simulates the hydrographical processes including the evaporation, the transpiration, the infiltration, the sensible and latent heat flows and the radiation. It simulates the temperature and humidity on a vertical profile starting from surface until a depth of 3.75 cm in the ground. At the same time, dynamic climate of the ground calculated by CLASS, product feedbacks interactively with the basic variables of LCM. The coupled system atmosphere-ground produces a climate on a column starting from the ground to the stratosphere high level (100hPa). Starting from LCM model, we used the aerological data of Maniwaki covering sixteen years period, from 1988 to 2004. These data are treated by a program interpolating the aerological data, from the surface to 100hPa level to assimilate data and the dynamic tendencies evolution of the temperature, moisture, the wind and the pressure.
Show more

34 Read more

Acupuncture for the Treatment of Hot Flashes in Men with Advanced Prostate Cancer

Acupuncture for the Treatment of Hot Flashes in Men with Advanced Prostate Cancer

PURPOSE: To test the safety and efficacy of acupuncture in reducing hot flashes in men with advanced prostate cancer (CaP) undergoing androgen deprivation therapy. METHODS: A single-arm, pilot study was undertaken to evaluate acupuncture treatment for hot flashes experienced by CaP patients undergoing hormonal therapy. Sixteen advanced CaP patients undergoing androgen deprivation therapy (ADT) received standardized full body and auricular acupunc- ture 1x/week for 14 weeks. Patients were evaluated at 0, 7, 14, and an additional 14-wk follow-up (F/U) (28-wks). Safety was measured by monitoring for adverse events over the treatment period. Serum testosterone was measured at 0 and 14-wks. Quality of life (QOL) was measured by the hormone domain of the Expanded Prostate Index Composite (EPIC), at the 0, 7, 14, and 28-wks and patient reported hot flash frequency was assessed weekly. Safety endpoints were serum testosterone and analysis of adverse events. Efficacy endpoints were scores on the EPIC and the number of pa- tient reported hot flashes. RESULTS: 17 patients were enrolled and 15 completed the trial. Of 15 evaluable patients the median age was 68 ± 8.19. Serum analysis demonstrated no change in testosterone at baseline 9.5 ng/ml ± 8.9 vs. end- point 14 ± 8.78 (p = 0.101). No adverse events were reported. Data analysis of the EPIC demonstrated a trend toward improvement after 7 wks and a significant improvement following 14 wks of acupuncture (p = 0.01). Analysis of patient reported frequency showed a significant reduction in the number of hot flashes at 7-wk (6, p = 0.04), 14-wk (2.6, p = 0.001), and 28-wk F/U (3.2, p = 0.01) as compared to baseline 9.57 ± 3.98. CONCLUSIONS: The administration of acupuncture in men with advanced CaP appears to significantly decrease the frequency of hot flashes. No serious ad- verse events were noted and serum testosterone levels were unchanged from baseline suggesting that the mechanism of action of acupuncture for hot flash amelioration is not via increase in testosterone.
Show more

5 Read more

Assessment of Cloudsat Reflectivity Measurements and Ice Cloud Properties Using Ground-Based and Airborne Cloud Radar Observations

Assessment of Cloudsat Reflectivity Measurements and Ice Cloud Properties Using Ground-Based and Airborne Cloud Radar Observations

Another important aspect that needs to be addressed is that three of the five ground-based radars used in this study are operating at a frequency lower than that of Cloudsat (Darwin and Lindenberg at 35 GHz and CPOL at 5 GHz); therefore, they are less prone to the so-called Mie effects, which occur when the particle diameter is no longer negligible with respect to the radar wave- length. A statistical method is proposed in what follows to take this effect into account. The principle is to ‘‘convert’’ the 5- and 35-GHz observations into pseudo- 95-GHz observations. The rationale for doing this is that although there are some assumptions in this conversion calculation, it will certainly yield more comparable reflectivities than if no correction is applied. However, it is difficult to estimate how accurate this conversion is on individual profiles. A statistical evaluation of this cor- rection will be given in section 5. For this purpose, we use a large database of in situ ice cloud microphysical measurements of the ice particle size distribution gath- ered in different international field experiments (as de- scribed in Delanoe¨ et al. 2005), assume the Heymsfield et al. (2007) temperature-dependent mass–dimension relationship, and calculate radar reflectivity at the three wavelengths of interest for the present study by using Mie theory. For the Mie calculations, we have used the spherical assumption for size, with the maximum di-
Show more

26 Read more

FORECASTING SOLAR POWER INTERMITTENCY USING GROUND-BASED CLOUD IMAGING

FORECASTING SOLAR POWER INTERMITTENCY USING GROUND-BASED CLOUD IMAGING

University of Arizona Tucson, AZ 85721 ABSTRACT We report progress towards developing methods to forecast solar-power intermittency due to clouds using analysis of digital images taken with a ground-based, sun- tracking camera. We show preliminary results of block- motion estimation analysis applied to a sequence of sky images recorded in Tucson, Arizona. In addition, we discuss statistics of ramp rates and duration of cloud- induced intermittency based on the analysis of one year of photovoltaic power output data measured at one second intervals for a 2kW system.

7 Read more

Ground-based remote sensing scheme for monitoring aerosol–cloud interactions

Ground-based remote sensing scheme for monitoring aerosol–cloud interactions

An ample number of studies have been made to quantify the impact of aerosol concentration on cloud microphysical properties. Studies focusing on low-level liquid water clouds are often based on different methods and instruments. Be- cause of this, the temporal and spatial resolution vary signif- icantly. Observational studies of the aerosol effect on clouds use surface remote sensing instruments at specific locations (e.g. Feingold et al., 2003; Schmidt et al., 2014) or rely on a combination of both surface remote sensing and aircraft in situ observations (e.g. Garrett et al., 2004; Kim et al., 2008; McComiskey et al., 2009). To characterise the aerosol effect on a global scale, many research studies focus on the satellite remote sensing observations (e.g. Kaufman et al., 2005). Mc- Comiskey and Feingold (2012) summarised the broad scope of different methods and scales used. They concluded that a single measure of aerosol–cloud interactions (ACIs) used in climate model estimates of the radiative forcing yields widely fluctuating results. ACI is a single measure derived from observational data from varying scales and different as- semblies of instruments. Further, they concluded that ACI r
Show more

12 Read more

Prediction of In-Cloud Icing Conditions at Ground Level Using the WRF Model

Prediction of In-Cloud Icing Conditions at Ground Level Using the WRF Model

the following reason: there is a sink term for cloud water that is not taken into account in the WRF model simu- lations, which is observed in reality, namely droplet deposition on the ground (in-cloud icing/riming on trees etc.). In some cases this process might cause a significant loss of cloud water close to the ground, especially in ex- posed forested areas. However, the magnitude is highly uncertain and no parameterization of such a process has so far been documented. Keeping this in mind, we could expect an overprediction of SLWC close to the ground by the current model version, and thus it is difficult to draw firm conclusions when comparing the two schemes. We also note that there is a slight tendency to overestimate the high SLWC measurements and to underestimate the low SLWC measurements, particularly when using the Thompson or the Morrison scheme (Figs. 5 and 6). Pos- sible reasons for this behavior have not been attainable to identify based on the limited number of cases in this study. Further research with more cases would be nec- essary to address this issue.
Show more

15 Read more

Learning group patterns for ground based cloud classification in wireless sensor networks

Learning group patterns for ground based cloud classification in wireless sensor networks

values of our method with the other comparing methods. The following four points can be drawn through analyz- ing the experimental results. First, the proposed method achieves the highest classification accuracy. Second, the performance of our method is over 12 % higher than that of LBP and 8 % higher than that of DLBP because the proposed method takes advantage of the most frequently occurring patterns to capture descriptive information of cloud image. Third, comparing the proposed method with the SLBP approach, we can see that the former is over 5 % higher than the latter ones on the accuracy. It indi- cates that adding texture resolution variation information is helping to improve the classification performance. In addition, the confusion matrix shown in Fig. 5 provides a detailed summary of the performance of the proposed LGP algorithm.
Show more

6 Read more

Attenuation of visual evoked responses to hand and saccade initiated flashes

Attenuation of visual evoked responses to hand and saccade initiated flashes

The experiment comprised five conditions: two types of self-initiation conditions (i.e., button-press and saccade-initiated flashes) and their corresponding motor control conditions (i.e., button-presses and saccades without consequent flashes), and an externally initiated condition (i.e., flashes initiated without participant input). Each condition was presented in a homogenous 80-trial block, and block order was randomized between participants. Three practice trials preceded each block to ensure participants understood the instructions

23 Read more

Deep multimodal fusion for ground based cloud classification in weather station networks

Deep multimodal fusion for ground based cloud classification in weather station networks

Then, we compare the proposed DMF with the other state-of-the-art methods for the multimodal information fusion, and the results are listed in Table 4. Note that “+M” indicates concatenating the visual features with multi- modal information. From Table 4, we can see that the proposed DMF outperforms the other methods and the classification accuracy achieves over 86%. A comparison between Tables 3 and 4 shows that the classification accu- racies in the latter are all better than those in the former. This demonstrates that the multimodal cloud information provides support for the ground-based cloud classification. This demonstrates that the multimodal cloud informa- tion is helpful for the ground-based cloud classification. The visual features and the multimodal cloud informa- tion are complementary and therefore fusing them could obtain the completed information of ground-based cloud. The improvement of DMF exceeds other methods, which verifies the effectiveness of the fusion algorithm.
Show more

8 Read more

Pilot Evaluation of Black Cohosh for the Treatment of Hot Flashes in Women

Pilot Evaluation of Black Cohosh for the Treatment of Hot Flashes in Women

Currently, the known information regarding the use of black cohosh is limited to several older European trials [15 – 19,26] and one recent placebo-con- trolled randomized trial conducted in the United States. [20] The European trials were composed of both prospective and placebo-controlled randomized trials. Hot flash symptoms were reportedly improved in the majority of women after a 4-week course of therapy, and the symptoms continued to improve over 12 weeks. A recently completed placebo-controlled trial, however, was unable to confirm the activity of the prior European trials. This American trial, however, did find a significant decrease in sweating among women taking the black cohosh, a finding that was also prominently observed in our pilot study. Because excessive sweating is a common and often debilitating symptom that accompanies hot flashes, an improve- ment in this clinical manifestation of menopause would be a welcome relief to many women.
Show more

7 Read more

Flashes from the Past: The Origin and development of banking supervision in Bulgaria

Flashes from the Past: The Origin and development of banking supervision in Bulgaria

For the first time in the Bulgarian banking history, the Bank Deposit Guarantee Act, adopted on 4 January 1931, stipulated the establishment of special authority – Bankers Board which wa[r]

16 Read more

Patterning of wound-induced intercellular Ca2+ flashes in a developing epithelium

Patterning of wound-induced intercellular Ca2+ flashes in a developing epithelium

FIGURE 4. (A) Color-coded point cloud of 12,349 cell areas from three, 3 rd instar wing imaginal discs. Note the observable qualitative increase in cell area with increasing distance from pouch center along the radial PD axis. (B) Color-coded point cloud of cell fractional anisotropies from the same population of cells as in (A). Note the observable qualitative increase in cell anisotropy with increasing distance from pouch center. White ellipses in (A) and (B) show location of z = 0.5. (C, D) Boxplot analysis of cell morphology. Red lines represent median values of each category. The upper and lower ends of each box represent the quartiles at 25% and 75% probability respectively. Dashed lines indicate range of the data. Outliers are plotted as red crosses. Sample size for each category is listed below the bin. (C) Boxplot of cell area for cells classed as being either central (0.5 < d) or peripheral (0.5 d). Cohen’s d = 0.6, indicating a medium effective difference between the means. (D) Boxplot of cell anisotropy. Cohen’s d = 0.4, indicating a small effective difference between the means.
Show more

37 Read more

Areas for improvement in community optometry : flashes and floaters take priority

Areas for improvement in community optometry : flashes and floaters take priority

indirect ophthalmoscopy can examine patients who present with new onset flashes and/or floaters without visual loss. Prior to this, the guidance could have been interpreted to mean that any patient who presented with recent onset flashes and/or floaters should be referred to an ophthalmol- ogist within 24 h, even if the patient’s examination was normal on dilated slit lamp indirect ophthalmoscopy and the patient had no other signs of retinal detachment. This amended version clarifies that it is the competence of the examining practitioner that is important rather than their professional designation. This reduces the burden to refer patients unnecessarily where a practitioner is confident that there is no retinal tear or detachment.
Show more

11 Read more

The spatial pattern of bioluminescent flashes in the polychaete Eusyllis blomstrandi (Annelida)

The spatial pattern of bioluminescent flashes in the polychaete Eusyllis blomstrandi (Annelida)

In the present study, we have used video imaging at a fre- quency of up to 100 frames/s to obtain information about the sites of luminescence and the kinetics of light emission: changing[r]

12 Read more

Flashes from the past: The Origin and development of banking in Bulgaria

Flashes from the past: The Origin and development of banking in Bulgaria

Thus it became the largest credit institution in the banking system of the country, with the exception of the BNB and the Bulgarian Agricultural and Cooperative Bank, and had a leading r[r]

17 Read more

Temporal integration of light flashes by the human circadian system

Temporal integration of light flashes by the human circadian system

Flashes that are 2 milliseconds in duration, such as those used in this study, are faster than the pupil constriction response (73). While the pupil constricts after the flash occurs, we have found (data not shown) that there is a persistent pupillary constriction for 29.5 ± 3.24 seconds (n = 4) after an individual flash, thereby reducing the overall input to the retina, especially for flashes with an ISI under 15 seconds. Taking into account pupillary con- striction induced by both continuous and different sequences of light flashes, continuous light would still contain 850 to 18,000 times more light than the sequences of flashes used in this study. We could have, as many laboratories do, used an antimuscar- inic agent to dilate the pupils to avoid the pupillary light reflex and keep it from interfering with the amount of light striking the retina. Given the potential effect of antimuscarinics on the phys- iologic properties of retinal ganglion cells (74), we feel that the use of such agents would have created greater uncertainty in the interpretation of our results.
Show more

11 Read more

Show all 10000 documents...