Hassan Lashkari; Zahra Hojjati
Volume 21, Issue 82 , September 2012, , Pages 14-21
Abstract
In order to investigate synoptic-dynamic situations which results in thunder storms in South Western parts of the country, data were exploited from 16 synoptic stations in South West of Iran during a 10 year statistical period (1996-2005). Fitting the precipitation data, six types of severe storms were ...
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In order to investigate synoptic-dynamic situations which results in thunder storms in South Western parts of the country, data were exploited from 16 synoptic stations in South West of Iran during a 10 year statistical period (1996-2005). Fitting the precipitation data, six types of severe storms were identified. Exploring the exploited systems, two general patterns were identified for thunder storms with severe precipitation. The first pattern follows integrated systems pattern, so a ridge from North West Africa to Scandinavia causes cold weather falling on the Mediterranean Sea and deepens the Mediterranean trough, which in turn strengthen the East Mediterranean low altitude center. Continuous cold weather falling on this cyclone center increase pressure gradient in east Mediterranean area and makes penetration of 500 hecto Pascal trough toward middle Red Sea possible. Increased temperature gradient over North Africa and the Red Sea strengthen Sudanese system and while moving toward North of this system integrates with low pressure Mediterranean system and results in unsustainability in West and South West Iran. The Second pattern is a low pressure Sudanese one. Low pressure Scandinavian system result in cold weather of pole neighboring latitudes falling into lower latitudes. Azore anticyclone which is formed over North Africa transfers cold weather to North Africa, aggravates unsustainability, strengthen Sudanese system and creates a weather front. Thunder storms require access to hot and humid weather which is injected into the area due to the proximity of Southern seas.
Hossein Sarami; Leila Salaki
Volume 14, Issue 56 , February 2005, , Pages 43-49
Abstract
In this paper, the concept of Thermal Island has been discussed in general. First of all, the definition of the city’s thermal island and its history have been presented using illustrations and diagrams. Next, the climate variables affecting thermal islands have been considered. The purpose of ...
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In this paper, the concept of Thermal Island has been discussed in general. First of all, the definition of the city’s thermal island and its history have been presented using illustrations and diagrams. Next, the climate variables affecting thermal islands have been considered. The purpose of the research is to introduce the city’s thermal island or the point of maximum of heat in the city, which mostly includes the city center. The term “thermal island” refers to the fact that city is warmer than its suburbs and surrounding area, which in some cases can show in a difference in temperature of 5-8 ° C. The research method in the paper is documentary, secondary and with the help of utilization of electronic sources and various websites. In addition, the hypothetical factors that create the cap layer covering the city’s thermal island are mentioned, and the radiation level in the urban area, its comparison with the suburbs and the effects it has on human health and the environment have been studied. Finally, strategies for dealing with Thermal Island through improving public behavior in relation to protecting the environment, developing green space, etc. have been examined and proposed.
