مهدی مدیری

Hail phenomenon is one of the hazardous weather phenomena that can make the highest amount of damage to farms, gardens, cars, rooftops, etc. in a very short time (a few minutes), depending on the diameter of the particles. One of the best ways to study this devastating climatic phenomenon is the use of atmospheric instability indices. The indices which are calculated with the help of radiosonde data give a fairly comprehensive vision regarding the occurrence of such phenomenon. In this study, the incidence of moderate to severe hail is investigated in the period of 1990-2010. First, the atmospheric codes related to hail phenomena were applied to extract the data, then radiosonde data in intended time were received and applying the RAOB software, the physical status of atmosphere was studied. In the studied period, two hail examples were reported on November 27, 2008 and December 5, 2008. In the first instance of hail that occurred on November 27, 2008, the status of some indicators was calculated and it was found that LCL was at an altitude of 284 meters, CCL at an altitude of 1582 meters, LFC at an altitude of 6230 meters, the ice surface at an altitude of 3278 meters, the LI index was -0.2, the K index was 25.7 ° C, and PWC was 28 mm. In the above mentioned conditions, there was a hail with a diameter of 25.4 mm. In the second instance of hail that occurred on December 5, 2008, the status of some indicators was calculated and the results showed that LCL was at an altitude of 280 meters, CCL at an altitude of 1762 meters, LFC at an altitude of 2271 meters, the ice surface at an altitude of 2771 meters, the LI index was -1.4, the K index was 27.1 ° C, and PWC was 23.6 mm. In the above mentioned conditions, there was a hail with a diameter of 3.6 mm. Given that in many ways, the status of most atmospheric indicators in the two above examples of hail were close to each other, it turns out that in similar circumstances, the greater the distance the ice level gets to the summit of cloud, the greater is the probability of hails larger in diameter. The value of this distance for November 27, 2008 was at approximately 6384 meters and for December 5, 2008, it was at about 5012 meters.

Due to its neighborhood with Afghanestan and the subsequent problems of this country such as insecurity, weak economic conditions, and lack of proper border monitoring, Khorasan Razavi Province has always been the inhabitat of numerous foreign nationals. Legal and illegal entry of these people has created plenty of issues from different economic, social, and cultural aspects for the citizens of this province. Negative consequences arising from the presence of foreign nationals on one hand and threats that may form from the Trans powers (using the nationals) have emphasized the necessity of considering the passive defense issue. So, one of the issues that requires further investigation is the security implications of foreign nationals in Khorasan Razavi province in terms of a passive defense approach. The main question of the current research is that of regarding the passive defense viewpoint, how the presence of the foreign national affects the security of Khorasan Razavi province and the Islamic Republic of Iran in general. This study has a cross-sectional study approach and through library studies, along with a comprehensive perspective, different threats are identified in the field. Proposing practical solutions, it attempts to take effective measures in controlling such consequences.

Passive Defense is a set of civilian efforts performed to enhance deterrence, reduce vulnerability, sustain essential activities, promote national stability, and facilitate crisis management against military threats of an enemy. Since in battles, sensitive and critical areas of cities are of paramount importance,it is clear that in military agressions, a large part of threats are focused on cities and their urban facilities and equipment, especially fuel centers. As a result, consideration of passive defense while planning cities has a significant role in reducing the vulnerability of cities and their urban elements as well as facilitating the urban crisis management. It also provides the citizens resistance threshold under possible enemy invasion and natural malicious agents. Hence, this article reviews and analyzes the current situation of gas distribution centers and evaluates their positioning across the city of Mashhad with regard to passive defense approach. However, as far as there is no clear- cut criteria for organizing fuel centers with passive defense approach, the Delphi method is used to select the desired criteria in which on the basis of the final comments of the experts, four critera- performance, access, hazards and security election and spatial organization of the fuel tanks and petrol stations- are analyzed using AHP model and GIS spatial analyzes. Accordingly, it can be said that the assessment of the current status of the urban fuel stations in Mashhad indicates that no area of the city enjoys all measures of passive defense (performance, availability, security, and risks). Likewise, the results indicate that the distribution of these centers in the city are mostly consistent with the factor of access. taking into account all the criteria, it is the ​​North West of Mashhad which has the highest utility than other areas. It is followed by the east of Mashhad and ​​the Northeast and the middle east of the city, respectively. Accordingly, it could be stated that ignoring an efficient design for determining the optimum location of the site construction with a passive defense approach results in an inappropriate and naive spatial distribution of the stations leading to an increased security and environmental risks of the city.