Number Of Thunderstorms Research Articles

ОЦЕНКА КЛИМАТИЧЕСКИХ ФАКТОРОВ РИСКА ПОЖАРНОЙ ОПАСНОСТИ ЛЕСА НА ИССЛЕДУЕМЫХ ТЕРРИТОРИЯХ ВОРОНЕЖСКОЙ И КАЛУЖСКОЙ ОБЛАСТЕЙ В СЕЗОН 2022 Г.

Forest fires are considered to be an element of the global development of the biosphere, a factor that should be taken into account when analyzing climate change and choosing actions to mitigate its negative consequences. The paper provides an assessment of climate-associated fire hazard risks in the 2022 season for the study areas located in the Voronezh and Kaluga regions. The source material for the study were average daily and specific-term observations of the Voronezh and Sukhinichi weather stations, representative for these areas, for the fire season from April to October 2022 as well as their long-term average monthly data obtained for the 56-year period 1966–2021. The methodological approach is based on calculations of the values of monthly normalized anomalies for five factors (air temperature, amount of precipitation, relative air humidity, wind speed, and the number of thunderstorms) and their subsequent comparative climatic analysis with the data from 2022. The results of the analysis made it possible to provide a clear quantitative description of the structure of the climate-associated fire hazard risks development for each month of the 2022 season according to these meteorological parameters relative to long-term climatic conditions. An additionaltransition from normalized anomalies to a score-based risk assessment provided the possibility to obtain approximate integral estimates of climate-associated risks for a complex of all the five factors simultaneously, for each month and the entire fire season for both study areas. The findings presented in the article are likely to be of interest to specialists in forestry, applied climatology, students majoring in disciplines related to the study of forests, forestry, and forest industry, and may also benefit a wide range of specialists in geographical, biological, ecological, and environmental fields.

Research on Thunderstorm Identification Based on Discrete Wavelet Transform

Lightning has been one of the most talked-about natural disasters worldwide in recent years, as it poses a great threat to all industries and can cause huge economic losses. Thunderstorms are often accompanied by natural phenomena such as lightning strikes and lightning, and many scholars have studied deeply the regulations of thunderstorm generation, movement and dissipation to reduce the risk of lightning damage. Most of the current methods for studying thunderstorms focus on using more complex algorithms based on radar or lightning data, which increases the computational burden and reduces the computational efficiency to some extent. This paper proposes a raster-based DWT (discrete wavelet transform) method for thunderstorm identification, this method uses DWT, CFSFD (clustering algorithm for fast search and finding density peaks) algorithm and ADTD (active divectory topology diagrammer) lightning location data for thunderstorm identification. The advantage of this method is that it supports different spatial resolutions and can identify any shape and number of thunderstorms at the same time and in the same area. It is effective in eliminating some of cluttered, scattered lightning data and extracting dense areas of thunderstorms. Furthermore, the method has a time complexity of O(n), and the computational efficiency is significantly better than the current TITAN (thunderstorm identification, tracking, analysis, and nowcasting) algorithm, which provides a good basis for subsequent extrapolation studies of thunderstorms.

Study of thunderstorm activity in Volyn Region and in Ukraine using the data of Blitzortung online resource

The article contains the results of statistical and graphical analysis of thunderstorm activity in Ukraine and within Volyn Region, in particular, following the study of the dynamic maps archive available at the online resource Blitzortung.org (lightnings and thunderstorms in real time). It describes the principles and results of activities of Blitzortung.org, a community of lightning direction sensors owners and users, and presents the developed algorithm of the methodology of reading dynamic maps available at this resource.
 Regional analysis of the archival maps on the website Blitzortung.org for 2008-2019 for the territory of Volyn Region made it possible to establish the following changes of the thunderstorm activity dynamics: the total number of thunderstorm days more than doubled (from 30 to 68.3 days on average); the number of thunderstorms increased in April (it was a rare phenomenon earlier); the number of thunderstorms increased significantly in May, for some years the number of thunderstorm days in May reached certain summer months (June and July); most thunderstorms are of frontal origin, storm fronts come from the west, north and southwest. The number of frontal thunderstorms tends to increase, therefore indicating increased atmospheric instability and the number of natural meteorological phenomena associated with such instability; the average monthly number of thunderstorm days in Volyn Region also increased for all months of the year with no exception.
 The analysis of storm activity within the whole territory of Ukraine during the period of 2018-2019 indicated the presence of clear regional features and differences. The increase in thunderstorm activity is observed in the western (50-100%) and southern (15-50%) regions of the country, and partly in the north. The number of thunderstorm days in the eastern part of Ukraine is close to the climatic normal. At the same time, the analysis needs to be clarified and detailed throughout the whole network of meteorological stations of Ukraine whose data can be compared with the results of the study of archival maps available at Blitzortung.org.

Time distribution of thunderstorms observed at Odesa AMSC at the beginning of the 21st century

The article presents the results of the research of thunderstorm activity at Odesa AMSC for the period of 2000-2019. Under conditions of intense warming, thunderstorm activity responds to the changes of temperature, humidity, radiation regime and atmospheric composition. Modern climate changes that are characterized by rising air temperatures have a decisive influence on the conditions under which dangerous weather phenomena are formed, thus monitoring of the thunderstorms formation in Ukraine is of great importance.
 The research includes the analysis of synoptic conditions of thunderstorm activity formation such as air-mass processes, frontal activity, and studies daily and daytime variability of the number of thunderstorm cases for the given period. The results of everyday meteorological observations of atmospheric phenomena conducted by Odesa AMSC within the period of 2000-2019 were used as input data to determine the characteristics of thunderstorm activity over city of Odesa. In order to identify the presence, time and duration of thunderstorm activity aviation weather diaries AV-6 were also reviewed. Certain synoptic materials were used to analyze the types of phenomena. Such materials include interactive database ARMsyn, surface synoptic charts for the periods of observation before and during the thunderstorms.
 It was established that during the period under study air-mass thunderstorms were formed in 370 cases of thunderstorm activity observed at the given observation post. Frontal thunderstorms occur less often: 241 cases over 20 years. The largest number of such thunderstorms is cold front thunderstorms amounting to 129 cases. 75 of them were identified as occlusion front thunderstorms. The least frequent were warm front thunderstorms – only 37 cases constituting 15% of the total number of frontal formations.
 During the studied period a total number of 620 thunderstorm cases was recorded, 195 of which are dry thunderstorms. Considerable attention is paid to the daily and daytime variability of thunderstorm cases number recorded by Odesa AMSC. With relation to the daily variation, more thunderstorms are observed during daytime amounting to 393 cases, 130 of which are dry thunderstorms. Night thunderstorms amount to 227 cases, 65 of which are dry thunderstorms. With relation to daytime distribution, more thunderstorms were detected in the afternoon.

Trend Analysis and ARIMA Modeling to Assess Meteorological and Surface Parameters In Ranchi, India During Pre-Monsoon Months

The assessment of the human-induced climate change on a global level can be carried out only after the study of local and regional climate change patterns. This study was an attempt to establish a link between regional climate and the surface parameters. The study was carried out for Ranchi, India to assess the changes in climatic pattern over the years (1901-2016) and applied Mann-Kendall Trend analysis test. The pre-monsoon period was chosen due to high intensity and number of thunderstorms taking place in the study area. Maximum temperature (Tmax), minimum temperature (Tmin), rainfall (P) &diurnal temperature range (DTR) for the months (March, April & May) were studied, and a significant negative trend in Tmax and DTR was observed. Autoregressive Integrated Moving Average (ARIMA) model was applied to fit the datasets and predict 5 values for the meteorological parameters, and the model depicted positive temperature trends and negative rainfall and DTR trends in the future. Land surface process parameters such as sensible heat flux, momentum flux, frictional velocity, shortwave radiation, longwave radiation, and net radiation for Ranchi were also fit into the ARIMA model, and the fitness of the model and predictions were determined.

The Effect of the Canadian Shield on Cloud-to-Ground Lightning Density

ABSTRACTThe Canadian Shield is a large area of exposed bedrock that covers a significant portion of Canada. The focus of this research is on the Canadian Shield in northeastern regions of the Canadian Prairie provinces, the Northwest Territories, and northwestern Ontario. Observations of cloud-to-ground lightning flashes show a distinct reduction in lightning density when crossing the southern boundary of the Canadian Shield. Statistical tests were used to determine whether there was a statistically significant change between the average cloud-to-ground lightning density gradient near the Canadian Shield and away from it. Most regions had a statistically significant change at the 95% confidence level across the boundary. However, regions that contained large lakes or significant topography did not, suggesting that the large open water and rough topography have a greater effect than the Canadian Shield.Three reasons for the distinct change across the Canadian Shield were explored: less lightning is detected, less lightning occurs with the same number of thunderstorms, and less lightning occurs because fewer thunderstorms occur. Some evidence suggested that less lightning is detected because the Canadian Shield has lower electrical conductivity. The low conductivity distorts the lightning waveform and contributes to higher errors and lower detection efficiency. There is also some evidence that a sharp change in land cover from lusher, higher transpiring forest to sparser lower transpiring forest could be reducing the instability causing fewer, weaker thunderstorms.

A Review of Thunderstorm Trends across Southern Ontario, Canada

Despite their potential impact, trends in thunderstorm occurrence in Canada have not received scientific scrutiny, one of the reasons for this likely being lack of data availability. A previous study showed thunderstorm observations at eight staffed weather stations in southern Ontario, Canada, to be accurate for distances within 10 km. We used hourly thunderstorm data from these stations and one additional station to determine whether a trend exists in the thunderstorm record in this region. A Mann-Kendall test and Theil-Sen approach determined that although some stations do have trends in number of thunderstorm hours per year over this time, a consistent increase in the number of thunderstorms that might be expected in a warming climate is not seen. Daily precipitation totals and maximum wind gust speeds were also used as proxies for thunderstorm intensity, neither of which confirmed an increase in the intensity of thunderstorms at these sites over the time period.

The Impact of Climate Variables on Seasonal Variation in Hong Kong Inbound Tourism Demand

In this study, we quantify the link between climate variables, such as temperature, rainfall, humidity, number of tropical cyclones, and number of thunderstorms, and seasonal variation in the Hong Kong inbound tourism demand from mainland China, Taiwan, South Korea, and Japan using the average Euclidean distance (AED) statistics and tourism demand modeling approach. Seasonal variation is measured as the fluctuation in the number of tourists from one season to another. Based on the smallest AED value, results of this study showed that climate variables play a dominant role in shaping seasonal variation relative to season and country. The fluctuation of tourist numbers from one season to another is determined not only by climate variables (e.g., the temperature of Hong Kong vs. the temperature in the country of origin of the tourist) but also by economic factors, including price and income. The variation in the impact of relative temperature depends on the country of origin.

Variability of selected extreme meteorological events in Poland

The principal aim of this paper is to analyze the trends of the multi-annual course of the selected characteristics of extreme precipitation, snow cover and atmospheric thunderstorms in the second half of the twentieth century in Poland. The results of these investigations show that in Poland it is only possible to determine a weak decreasing trend of extreme precipitation events in the S and especially in the SW part of the country. In northern Poland, opposite, although similarly weak, trends have also been observed. It is assumed that the most essential features of long-term changeability of extreme precipitation include a higher than average number of days with extremely high precipitation during the 1960s and 1970s, a distinctly lower frequency of such days during the 1950s, 1980s and in the first half of the1990s. In Poland it is possible to distinguish four broad homogenous areas in terms of the long-term changes in the occurrence of extreme precipitation events. There is considerable regional differentiation when it comes to the occurrence of thunderstorms in Poland, and their long-term changeability does not show any clear trends. Only three stations have determined a weak increase in the number of thunderstorms during the last 120 years. In some stations, an increase in the number of days with thunderstorms during the winter seasons was also observed. There were no significant trends in extreme snow cover in Poland. The periods that contained large and small areas of extreme snow cover thickness occurred alternately. Since the winter season 1987/88, the area of extremely thin snow cover has remained at a relatively high level.

Global Lightning Variations Caused by Changes in Thunderstorm Flash Rate and by Changes in the Number of Thunderstorms

Global lightning activity is highly variable on many time scales. This variability is attributable to changes in the flash rate per thunderstorm, the number of thunderstorms, or a combination. The TRMM Mission offers lightning observations from the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) in space. Both are used to examine the response of these parameters to thermodynamic forcing of deep convection on the diurnal and annual time scales. On both time scales, the changes in the number of storms dominate the variations in total lightning activity. On the diurnal time scale, the mean flash rate appears to vary with cloud buoyancy, peaking in early afternoon and declining in late afternoon, but the contribution of number of thunderstorms is 2-3 times greater that the mean storm flash rate. On the annual time scale, almost all of the total lightning response is due to changes in the number of storms, with a negligible contribution from flash rate. Evidence is presented that the LIS/OTD 'area' is a meaningful objective identifier for a thunderstorm.

The gap-width distribution in lightning flashes

At high frequencies of the order of 10 MHz or more gaps in the noise radiation from lightning discharges follow a different distribution law dependent on whether or not the radiation emanates from a cloud or a ground flash. A detailed investigation has shown that the gap-width distribution for cloud flashes can be expressed byn(w) c = A exp (−0.575w) while the corresponding expression for ground flashes isn(w) g = B exp (−0.102w), wheren(w) c andn(w) g are the number of gaps occurring for a particular gap-widthw with cloud respectively ground flashes. The constantsA andB depend merely on the total number of flashes under consideration. For a given number of thunderstorms the two distribution laws intersect at a fairly well defined value ofw=11 ms. Gap-widths greater than this value can be attributed to ground strokes while shorter gaps seem to be connected with the noise radiated from cloud discharges. Based on this “critical” gap-width, ground flash counters have been designed that show good discrimination against cloud flashes.

A Model for Thunderstorm Activity: Use of the Compound Negative Binomial- Positive Binomial Distribution

SUMMARY A probability model for the number of thunderstorms occurring within a thunderstorm event (one or more thunderstorms) is presented. The model is applied to data gathered during the summer months at Cape Kennedy.

HAILSTORMS IN WISCONSIN

Abstract A climatological study of hailstorms is presented for the State of Wisconsin and for four first order weather stations: Green Bay, La Crosse, Madison, and Milwaukee. The analysis considers the geographical and time distribution of hail and the ratio of monthly average number of hailstorms to monthly average number of thunderstorms.

Dynamics of thunderstorms

The development of a thunderstorm which is essentially a convective phenomenon needs a cause for initial convection and then conditions for its maintenance once started. The possibility of the inherent instability due to potentially colder air superposed on potentially warmer air or the analogous case of extra injection of moisture in the lower layers in shown to be not applicable in nature and that causes for initial convection must be found elsewhere than in the potential density distribution. Some of the causes are non-horizontality of surfaces of equal temperature and equal humidity; and gradient of wind velocity. It is shown that upward rise of air produced by unequal heating of the ground, does not stop where the rising mass of air attains a density equal to that of the environment (hydrostatic equilibrium), but continues to rise higher till the momentum developed is reduced to zero. The extent of over-shooting is nearly of the same order as the height between the initial level and the level of hydrostatic equilibrium. Once the condensation level is reached, it is well known that the convection will become regenerative due to the evolution of the latent heat of condensation. In the usual treatment of the problem, the ascending parcel of air is expected to condense at or before it reaches the level of hydrostatic equilibrium if it is to develop into a thunderstorm. The dynamical treatment outlined in this paper takes into consideration the overshooting of the parcel of air and thereby allows much drier air to reach condensation and thereafter maintain convection: and can thus account for a larger number of thunderstorms.

Vertical electric currents below thunderstorms and showers

In a previous paper an account has been given of apparatus which was found to be suitable for studying the discharge of electricity from a raised metal point in the strong electric fields which occur at the surface of the ground during thunderstorms and showers. The two methods of observation which were employed consisted, first, in measuring the quantity of electricity of each sign which was discharged from the point in a definite period of time, usually the duration of a storm; and secondly, in obtaining a continuous record of the current from the point throughout a storm. Observations on a number of thunderstorms and showers over a period of several months, by the first method, showed that there was a considerable preponderance of upward discharges of positive electricity, indicating that negative gradients of potential predominated at the surface of the ground in such disturbed weather conditions. Some examples of records obtained by the second method were also given. In the present paper, results obtained by the first method over a period of two years are discussed, the observations including all occasions, during that time, on which intense electric fields existed at the observing station for a sufficiently long time to cause a measurable quantity of electricity to be discharged from the point. (The smallest quantity which would be detected by the integrating device is about 0·1 milli-coulomb.) The preponderance of negative potential gradients during periods of intense electric field has been confirmed over the longer period of time. Records obtained by the second method are also described, and their bearing on the question of the polarity of the clouds is discussed. For this purpose, the method of observation is simply a convenient way of obtaining an unambiguous continuous record of the sign of the potential gradient, and a rough estimate of its magnitude, throughout periods of heavy rain. Finally, the problem of the total interchange of electricity between the earth and the atmosphere from known causes is re-discussed, utilising the results already given.

TORNADOES IN ARKANSAS, 1879–1926

Abstract SYNOPSIS The article presents three tables: One showing the place, date, and certain statistics regarding 225 tornadoes which occurred in Arkansas from 1879 to 1926; one showing the distribution of tornadoes by months and years; one showing the number of tornadoes by months from 1908 to 1926, the number of thunderstorms in Little Rock for the same period, and a comparison of tornadoes in Arkansas and thunderstorms at Little Rock. A chart showing the distribution of tornadoes over the State is given with arrows showing the direction of tornadoes at Fort Smith, Little Rock, Heber Springs, and Hot Springs. The chart and tables are discussed, also some of the larger features of topography and their probable effect on the courses and distribution of tornadoes. Ibis pointed out that tornadoes usually form in the southeastern portion of the LOW and move northeast-ward; and reasons are given for the movement of some tornadoes in other directions and for the occurrence of tornado families.

HAILSTORMS IN NEBRASKA

Abstract SYNOPSIS From a study of all available hailstorm records from one hundred and fifty cooperative Weather Bureau stations and the regular Weather Bureau stations in Nebraska it was found that the average number of hailstorms during the season April to September. The greatest number of hailstorms occur about a month later than the time of greatest rate of temperature increase in spring. The greatest number of thunderstorms is in June and the fewest in April. Although hail does not occur without a thunderstorm, but 7.2 per cent of all thunderstorms is accompanied by hail. The percentage is largest in April and least in August. Reports of hailstorms as large as hens' eggs, or even larger, are frequent, and although storms of such intensity are local, they cause considerable damage.

Chart VIII. Isobars, Isotherms, and Wind Directions. 7 a. m. (Eastern time). September 19, 1886. Figures indicate the number of thunder-storms in each state on this date

Chart VIII. Isobars, Isotherms, and Wind Directions. 7 a. m. (Eastern time). September 19, 1886. Figures indicate the number of thunder-storms in each state on this date

Chart IX. Isobars, Isotherms, and Wind Directions. 7 a. m. (Eastern time), August 16, 1886. Figures in each state indicate the number of thunder-storms in the state on this date

Chart IX. Isobars, Isotherms, and Wind Directions. 7 a. m. (Eastern time), August 16, 1886. Figures in each state indicate the number of thunder-storms in the state on this date