â â â  this paper attempts to investigate the relationship between 500hpa circulation patterns and weather types (coldest, warmest and raining) over 16 synoptic stations of mountainous region of iran. the mountainous region of iran covers about 670000 square kilometer (41 percent) of iran. in this paper have been investigated the relationship between circulation patterns in 500hpa level with we...

Relationships between transient upper-tropospheric troughs and warm season convective activity over the southwest United States and northern Mexico are explored. Analysis of geopotential height and vorticity fields from the North American Regional Reanalysis and cloud-to-ground lightning data indicates that the passage of mobile inverted troughs (IVs) significantly enhances convection when it c...

The Colorado Plateau, surrounded by a ring of mountains, has the meteorological characteristics of a basin. Deep, persistent potential temperature inversions form in this basin in winter. The formation, maintenance, and dissipation of these inversions are investigated using two to four times daily radiosonde data from the winter and early spring of 1989–90. In winter, inversion evolution is for...

The global evolutions of f oF2 anomalies were examined for three very intense geomagnetic storms, namely the Halloween events of October–November 2003 (Event X, 29–30 October 2003, Dst −401 nT; Event Y, 20–21 November 2003, Dst −472 nT), and the largest Dst storm (Event Z, 13–14 March 1989, Dst −589 nT). For Event X, troughs (negative storms) were clearly seen for high northern and southern lat...

A coherent synoptic sequence, mostly over North Africa, is identified whereby an upper-level midlatitude trough (in November–March) excites several days of quasi-stationary near-surface warming across the Sahara, leading to rainfall events northern Congo (NC), and perturbed weather more widely. Ahead NC events, composite sequences first identify troughs for near Iberia, followed by relatively q...

abstract: numerical weather forecasting models are used for forecasting and dynamic conditions analysis of atmosphere phenomena in recent years. this research investigates dynamic and thermodynamic conditions in heavier precipitation events in different synoptic patterns in the southern coasts of caspian sea using wrf model. database precipitation events were formed. super heavy and heavy preci...