Szentpéteri Mária

English

University of Szeged

C O M P A R I N G T H E A N N U A L C O U R S E O F T H U N D E R S T O R M F R E Q U E N C Y IN H U N G A R Y W I T H D A T A O B T A I N E D A H U N D R E D Y E A R S A G O b y Maria Szentpeter i MASZ enILA TAHARKEP2Ű F01SK0LA, S2EBED T o t h e m e m o r y of P r o f e s s o r P e c z e l y A aagyarországi zivatargyakoriság évi eloszlásának 100 évvel ezelOtt nyert adatokkal ttrténí összehasonlítása, fiz í968-77-es évek adatai szerint mutatkozó «agyarországi zivatargyakoriság évi menete és t közel 100 évvel ezelőtt kapott, Héjas f. által közölt eredmények között főbb vonásaiban nincs nagy különbség (lásd az 1., 2., és 3. ábrákat!). Ugy tűnik, hogy az általam készített statisztikához használt adatok talán megbízhatóbbak, vagyis a jelenkori "zivatar-mérés" szubjektív hibája mintha kisebb lenne, «int a 100 évvel ezelőttié. Talán ez lehet az egyik oka annak, hogy a 33. dekád körül egy kis lokális maximumot találtat. Héjas E. azon következtetése, miszerint "a zivatargyakoriság maximuma megelőzi a hőmérséklet júliusra esö maximumát", az 19&8-77-es adatok tökrében nem teljesül. In the main features there is not much difference between the annual course of the thunderstorm frequency in Hungary obtained fro* the data of the years 1968-77 and the results published by E. Héjas nearly a hundred years ago (see Figs. 1, 2 and 3). It seems that the recent data are more reliable, as if the subjective error of present-day "thunderstorm measurement" is less than the earlier one taken 100 years ago. Perhaps this nay be the reason for the fact that I found a small local maximum about the 33ra decade. £. Héjas's conclusion that "the maximum of thunderstorm frequency precedes the maximum of temperature in July" is not proved in the light of the 1968-77 data. During the past hundred years, the intensive studying of the annual • course of the phenomena of atmospheric electricity has, for certain rea-sons, fallen into the background. Probably these circumstances explain that relating to the above problem one can only find approaching reports at most, even in the university text-books. In connection with the annual course of the thunderstorm frequency in Hungary - nearly one hundred years ago - EHDRE HEJAS reported rather reliable data. In his book, published in 1898 LI], he precisely examined the atmospheric pressure, the wind, the tem-perature, the vapour pressure and the relative humidity, the cloudiness, the evaporation, the ozone and finally the precipitation on stormy days. In his examinations he took into consideration what kind of correla-tion is between storminess and weather situation, and which are those types of weather that lead to the intense developing of thunderstorms. After the satisfactory critical elaboration of data the collected from the territory of the country of that time £.. Héjas drew several conclusions which are worth reviving and comparing with the data of today. During statistical examinations it often occurs that the figures of the elements of the samples selected for the evaluation are not the same. In such cases, frequency distributions cannot be directly compared! this is why some sort of mathematical method must be applied to be able to directly compare the distributions. Since the number of the stations examined by me, and that of E. Héjas's stations differ, I transformed E. Héjas s monthly frequency values to the percentage of the annual frequency! so the obtained values (as relative frequencies) are independent from the number of the stations! so there is a possibility of direct comparison. I compared the obtained results to the data counted from the data of the years 1968-77 C23. This is demonstrated by Fig. 1. E. Héjas's results are taken from the tables of pages 108 and 109 of his book. However, I should like to remark that the title writing of the tables is not correct. It is probable that from the data of E. Hejas from the data of 1968-77 M A M J J A — Months -0 N Fig. I Annul I course oi thunderstores in Hungary in lonthly frequencies E. Hijas mixed the numbers of the thunderstorms with the numbers of the stormy days. For in his table he does not give the monthly and annual sums of the stormy days - as he writes in the title of his table - but the monthly and annual sums of the detected thunderstorms. E. Hejas also offers further possibility for comparison by having studied the annual course of thunderstorm frequency in taking them to pen-tads. Among his conclusions, I should like to emphasize that he experienced a decline about the 35'" pentad. He brought this into connection with the fact that in the 25-year annual course of temperature there is a well rec-ognizable decline about the SS'" pentad. Recognizing of such coincidences is very important, but we have to consider the fact that the mere coinci-dence is not a reason for us to conclude with absolute certainty that there is a relation of cause and effect between the two variables. For in such cases it often came to light that the two variables depend on the changing of a third (possibly several other) variable(s). It evidently means that it would be unwise to speak about the fact that the cause of the changing of one variable is the changing of the other one. The above-mentioned decline can be shown on the basis of the ¡968-77 data C2]. Since the frequency fluctuations are relatively great in the dis-tribution of pentadic breaking down, so I converted E. Hijas's data into units of ten days (decades), and compared to the decadal distribution counted from the data of the years 1968-77. In order to demonstrate the course of the two distributions, I drew the two distribution "curves" as equally high (by dividing them with the maximum values). It can be seen in 74 — Months Fig. 2 Annual course of thunderstorm in decadal frequencies (unit = taxiul decadal frequency) the figure that the courses of the two "curves" are almost the same. The above-mentioned decline at the 35'" pentad or 17-18"' decade, which still exists in the case of 15-day intervals but is no longer so expressed, is recognizable at both distributions, and in the case of a monthly course, it disappears already. In connection with the 2"" figure, I should like to draw the attention to the fact as well that on the basis of the data of the years 1968-77, at the time of the minor (5-, 10-,or 15-day) course demon-stration toward the end of November (at about the 33pentad) a little local maximum is also recognizable C23. Further examinations can be done also because there are a couple of stations among those of E. Héjas which occur among the stations examined by me, as well. These data are summarized in Table 1. It can be seen that, on the one hand, the average number of the thunderstorms is 22.4 for the sta-tions listed by E. Héjas; on the other hand, in my statistic the number is 25.02. The question emerges whether the two data series of Table 1, more precisely the two mean values, can be considered significantly different or not. The answer is NO. On fulfilling the two-model t-proof, it is obtained that the difference between the two values cannot be considered significant even in the case of 10 7. confidency" level. This means that the values of 22.4 and 25.02 are practically equal. It is immediately understandable from the fact that in Hungary the standard deviation of thunderstorm frequencies is roughly 3 for one station C23. For the stations in Table 1, so for Buda-pest, Eger, Nyíregyháza, Kalocsa and Szeged, E. Héjas gave, beside the annual number of the thunderstorms, even the average monthly thunderstorm 7 5 Table 1 The annual su«s of thunderstorm frequencies for 12 stations on the basis of the data of i. H6j»s and of the years 1968-77 Stations E. Hi.ias's data Data of the years 1968-77 Budapest 19.2 18.9 Eger 23.3 23.5 Kalocsa 21.0 18.8 Keszthely 23.9 27.5 Komárom 19.2 22.5 Makó 23.0 14.3 Mezőhegyes 20.8 27.6 Nyiregyháza 74.6 30.0 Sopron 20.9 27.0 Szeged 21.6 32.7 Szolnok 24.4 » 28.7 Zalaegerszeg 27.2 28.8 Sum totál 269.1 302.3 Average for one station 22.4 25.2 The italicized values are arithmetical means of two data published by E. H'ijas Table 2 Annual course of thunderstorm distribution with monthly frequencies for S stations. Among the data-pairs the first one is always of £. Htjas, the second is of 1968-77 1 II III IV V VI VII VIII IK X *I XII Budapest 0.00 0.0? 0.32 1.20 3.92 5.12 3.76 3.20 1.16 0.40 0.00 0.04 (Szabadság- 0.00 0.4Ó 0.20 1.10 2.80 4.20 3.B0 4.40 1.80 0.00 0.20 0.00 hegy) ' Eger 0.05 0.09 0.35 1.61 4.48 6.26 5.18 3.52 1.30 0.30 0.13 0.00 0.00 0.W 0.50 1.50 3.80 6.40 6.70 4.40 1.70 0.10 0.30 0.00 Nyíregyháza 0.00 0.12 . 0.42 1.42 3.88 6.79 5.87 3.71 1.13 0.29 0.04 0.00 :0.00 0.20 0.20 1.50 5,90 6.80 7.30 5.10 2.S0 0.40 0.10 0.00 Kalocsa' • 0.00 0.05 0.19 1.00 3.33 5.19 4.62 3.52 1.43 0.62 0.10 0.00 0.00 0.30 0.40. 1.30 2.70 4.40 4.00 3.60 1.70 0.20 0.20 0.00 Sieged 0.09 0;00 0.Í6 .1.70 3.78 3.53 4.35 2.74 1.96 0.65 0.17 0.04 0.00 0.00 0.80 1.60 6.10 7.60 6.70 7.10 2.00 0.30 0.50 0.00 Average 0.03 0.Ú6 0.32 1.39 3.88 5.74 4.76 3.34 1.40 0.45 0.09 0.02 for one 0,<*> 0.20' 0.42 1.40 4.26 5.88 5.70 4.92 1.94 0.20 0.26 0.00 fetatiqp -Annual gum for one station- - 21.46 25.18 frequencies. The data used for the annual period are summarised in Table 2. The difference between the two distributions can be seen in Fig. 3. Here the most apparent thing is that the distribution counted from E. Héjas's data is sharper to the left than the distribution obtained from the data of the years 1968-77. This fact can be observed in Fig. 1, and even in Fig. 2. From this shift to the left E. Héjas concluded - wrongly in my opinion -that "The majority of our thunderstorms come in early summer, and so the maximum of thunderstorm frequency precedes the maximum of temperature coming in July". According to E. Héjas's statistics, the number of thundei— storms for one station in Hungary is 22.2. He himself considered this value only a lower approaching because at several stations only the strongest thunderstorms could be recorded, the farther ones were not taken into con-sideration. He chose 1.5 as tolerance in the number of thunderstorms (he did not give any reason for his choice). In the chapter "Thunderstorm Stat-istics", it was average values as about 25 and 26 average value - instead of the above-mentioned number of thunderstorms - which he considered to be the most probable estimated values. These latter values correspond very well with the average values obtained on the basis of the 1968-77 data [2]. E. Héjas gives 19.2 thunderstorms annually for the northern slope of Várhegy in Budapest, and this is almost equal to the mean value of 18.9 of station on Szabadsághegy obtained on the basis of the data of the years 1968-77. In C3,4] I have dealt in greater detail with the identities and differences relating to the spatial distribution' of the thunderstorm frequency in Hungary, a swell as to the annual courses óf the fulguration and hail frequencies. In the main features there is not a great difference I — M o n t h s — Fig. 3 Ainua/ distribution of thunderstorts on the basis of the data fro• the toms of Budapest, iger, Hyiregyhiza, Kalocsa and Szeged in aonthly frequencies 7 7 between the annual course of thunderstorm frequency in Hungary obtained from the data of the years 1968-77 . and the results obtained by £. Héjas nearly ¡00 years ago (see Figs. 1, 2 and 3). It seems that the data used for my statistics are perhaps more reli-able; that is, it seems as if the subjective mistake was smaller in present day "thunderstorm measuring" than in the one 100 years ago. Perhaps this may be one of the reasons for the fact that I found a small local maximum around the 33''" decade. £. Héjas 's conclusion that "the maximum of thundei— storm frequency precedes the maximum of temperature, falling in July" is not confirmed by the data from 1968-77. References [11 I. H[JAS: A zivatarok Hagyarországon az 1671-tfil 1895-ig terjedő seqfigyelések alapján. (Thunderstorira in Hungary on the basis of the observations extending froti 1871 to 1895).- Budapest, 1898. 121 If. S2ÍHTFE1ÍRII A zivatargyakoriság évi aenete hagyarországon. (The annual course of thunderstore frequencies in Hungary.) - Juhász 6yula Tanárképző'Főiskola Tudoaányos Közleményei, Szeged, 1982. 95-104. [31 H. S2FHTPETCR1: A zivatargyakoriság területi eloszlása Hagyarországon. (The regional distribution of thunderstore frequency in Hungary.) - Juhász 6yula Tanárképző Főiskola Tudoaányos Közleményei, Szeged, 1982. 105-113. [4] H. SIÍHIPUÍRI: Villogás- és jégeső-gyakoriság évi eloszlása Hagyarországon az 1948-77-es évek adatai alapján. (The annual distribution of the frequency of figurations and hails in Hungary on the basis of the data of the years 1948-77.I - Juhász 6yula Tanárképző Főiskola Tudoaányos Közleményei, Szeged, 1983. 85-94. 7 8 

Comparing the annual course of thunderstorm frequency in Hungary with data obtained a hundred years ago : to the memory of professor Peczely

http://acta.bibl.u-szeged.hu/16815/1/climatologica_021_023_073-078.pdf

Comparing the annual course of thunderstorm frequency in Hungary with data obtained a hundred years ago : to the memory of professor Peczely

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