Abstract
The main purpose of this study is to investigate temporal and spatial distribution of thunderstorm frequency in Iran. In order to do study, observed statistical data of the present weather codes of thunderstorm (17, 29, 91 - 99) in 50 synoptic stations around the country were used in a 35 years statistic period (1979-2013). The results of the study showed that the phenomenon occurs mostly in southwest, west and northwest regions of Iran. Thunderstorm occurrence reduces when moving toward east. Maku station in northwest of Iran shows the maximum thunderstorm frequency during the statistical period (mean annual of 31). Jask station in southern Iran (mean annual of 2) has shown minimum thunderstorm occurrence during the statistical period. In the eastern regions of Iran, Torbat Heydarieh station revealed higher frequency than the other stations which was because of high mountains like Qaenat. In terms of temporal distribution, spring showed the highest frequency of the phenomenon. In monthly scale, the maximum frequency of hail downfall happens in April and May. In hourly scale, the maximum occurrence of thunderstorm observed at 12 - 18 p.m. for UTC time.
Highlights
Thunderstorm is one of the complex and severe climate risks which results in many casualties in addition to destruction of a great number of crops and utilities in many different parts around the world
Regarding the table it is shown that in terms of average, the most frequency of thunderstorms in an annual scale was 31.5 in Maku station and the least was seen in Jask station with 2.2
Results show that the spatial distribution of thunderstorm in Iran is a function of time and topographical conditions of the considered region
Summary
Thunderstorm is one of the complex and severe climate risks which results in many casualties in addition to destruction of a great number of crops and utilities in many different parts around the world. In 1953-1957, financial damages from thunderstorm were estimated more than 3.6 billion dollars. Thunderstorms take the second rank of natural disasters in terms of damage level to the US economy after Tornados [1]. How to cite this paper: Ghalhari, G.A.F. and Shakeri, F. Shakeri elements of thunderstorms are as follow: Updraft and strong turbulence, micro bursts and Gustian fronts, cyclones and tornados, lightening and thunders, hail and heavy rainfall. Two conditions are needed in order to form strong conventions of humidity like those occur in thunderstorm: conditional instabilities and ascending mechanism. Two requirements are needed in order to form strong conventions of humidity like those occur in thunderstorm: conditional instabilities and ascending mechanism. Conditional instabilities mean a particular state which is provided by the environment to form thunderstorm. Ascending mechanisms are as follow: Boundaries between the air mass, fronts, dry lines, sea breeze fronts, Gustian fronts from other thunderstorms and other ascending mechanisms such as atmospheric boundary waves, mountains and surface heating of the regions in a local scale [1]
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