Climatology
hassan lashkari; Aliakbar Matkan; Majid Azadi; Zainab Mohamadi
Volume 22, Issue 64 , September 2018, , Pages 247-266
Abstract
As a result of Iran’s geographical position towards atmospheric general circulation, most of its area has an arid or semi-arid climate. In this research, the author has calculated precipitation start using the daily precipitation information obtained from 30 stations located in 8 southern and south-western ...
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As a result of Iran’s geographical position towards atmospheric general circulation, most of its area has an arid or semi-arid climate. In this research, the author has calculated precipitation start using the daily precipitation information obtained from 30 stations located in 8 southern and south-western provinces of Iran during a 36 year statistical period and of course, based on selected criteria. In ten years, precipitations have started sooner than normally expected. Entire up to 700 HPa levels and sea level pressure maps belonging to 1st of September till the day of precipitation start have been illustrated with Grads software using atmospheric data obtained from Ncep/ncar site. Results of several objective observations of maps manifest that early precipitations in south and south-west sides of Iran are generally occurred in three main patterns. Pattern A) as African sub-tropical high pressure passes above central Mediterranean in a northward move and its eastern trough integrates with migratory anticyclone (deployed on the north side of Caspian Sea), it provides the necessary context for cold advection to move towards north of African high pressure. Afterwards, the migratory anticyclone trough integrates with anticyclone ridge of Arabian high pressure and therefore a very suitable situation is provided for advection of moisture to move inside the Sudan low system. In pattern B) almost thirty days before start of precipitations, the Azour anticyclone adopts a northward movement.
Urban Planning
Hasan Lashkari; Yousef Zarei; Mohammad Moradi
Abstract
To study the synoptic - thermodynamic characteristics of the cloud mechanism in Azerbaijan in 2009-2000 period using the average rainfall of 15 mm and inclusive precipitation, 13 days was chosen indicators. To evaluate the development of the synoptic systems, sea level pressure and high levels of 850 ...
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To study the synoptic - thermodynamic characteristics of the cloud mechanism in Azerbaijan in 2009-2000 period using the average rainfall of 15 mm and inclusive precipitation, 13 days was chosen indicators. To evaluate the development of the synoptic systems, sea level pressure and high levels of 850 and 500 HP respectively. 850 and 700 hPa specific humidity of the review process of cloud formation and water vapor transmission to the regional case study was used. To review upward movement that causes the formation of convective clouds to grow vertically or thickness, the vertical component of wind velocity in the coordinate system pressure at the level of 500 HP, were used. The stable and unstable atmospheric conditions were analyzed based on the graph skeu-t Tabriz. Synoptic results showed that the samples case study, the formation mechanism of the regional systems that have passed careful, depend on many factors. As a result of the deepening trough in the middle level of the high latitudes near the poles towards the south of the Mediterranean, the Red Sea along the meridian pressure inverted trough extends towards the south of the Mediterranean Sea. The northern part of the trough to trough height of the middle level, a Low pressure systems form when cold air and moisture from the middle latitudes of the Southern latitudes. Warm weather and cold fronts associated with this system is that, by moving his hand from the East Azerbaijan passes are causing precipitation in the region. Thermodynamic results showed that the thickness of the cloud and precipitation intensity and positive relationship is nonlinear. That the amount and intensity of precipitation than the thickness of the cloud, other factors are involved. The results of thermodynamic parameters showed that the convective rise in spring and autumn with warm and cold fronts are causing heavy rainfall in the region.
