Climatological elements
By study and searching in this region, we should differentiate between the elements, and regional factors. temperature – pressure and radiation, each of them concern to a regional element. The combination of these elements that is a physical condition of atmosphere like temperature, raining or the amount of clouds in the sky, are regional elements. But elevation – langitude – latitude. mountainside and plant covering, which are important in searching are, concerned as regional factors. Here we study the norms of province regions that are a total conclusion of available statistics of atmosphere elements.
The air temperature:
Searching the different parameters of temperature is very important in planting programs and improvements, also industrial projects, and city building. The province of chaharmahal and Bakhtiary is one of the coldest of all. The annual average of temperature in different parts is under the cause of different regional factors. In the center of province, Shahrekord, the average temperature is 11.5 degrees centigrade - Borujen 10.5, in colder places like Koohrang 9.2 and at warm places like Lordegan is 15.2 . In Chaharmahal va Bakhtiyary province, usually the warmest month is July and the coldest is January. The Min absolute temperature in some of the places like Dezzak has been reached to -34.5 degrees centigrade. In the center of province the Min absolute temperature recorded during the last 30 years in Shahrekord -32 and the Max has been 42 degrees centigrade. The most absolute temperature that has been observed in lordegan in 47.5, that is explanatory of a warm condition in this place of the province.
Amount of freezing days:
If during a day and night (24 hours) the Min of temp is 0 (zero) or under that, we call it a freezing day. Freezing days are different in the different parts of the province. The least of them is in lordegan with 83 days (period of 1972-2000) and the most of them in Dezzak with 140 days (period of 1972-2000). Naturally in mountains having no signal – man, it may be more than what we recorded. Freezing days in the center of the province,shahrekord,are 124 days and Koohrang 132 days, Borujen 132 days and Lordegan 113 days respectivly, (1958-2000). On June - July - Aug, the cities are without freezing days. Most of the freezing days are in January. Freezing taking place in spring leads to frost – bite of blossoms. This damages a lot of trees and gardens and fields. So this parameter is very important.
Relative humidity:
Because of heights and huge sources of water also rivers and entering the humid flows (rain – snow), relative humidity is in a good condition. The average of relative humidity is representing in percent. This is %46 for Shahrekord - %38 for Borujen -%45/7 for Lordegan -%46 for Koohrang %50 for Avargan-%46 for Dezzak -%48 for Emam gheis – and %50 for Zamankhan. Considering the distance between the station and moisture sources like rivers, this quantity clarifies the Condition around the stations.
Precipitation:
The province of Chaharmahal va Bakhtiary is situated at the foot of middle Zagros and is one of the submergible places in our country. The kind of precipitation in the province is different from one place to another. For example in high regions, half of the rain is freezing. the rate of snowfall coefficient in the height of Koohrang in different years, has been different from %34 to %59. So the effects of the combination of rain – and snow over the climate is observable. Time of precipitation in this province is like the west of Iran. Most of the rains are between December and the end of April. The dry season of the province is Conforming with summer. The maximum month precipitation in cities and different places of province is most in January – February and sometimes in march or December and rarely it rains in April. These are usually taking place at the higher places of the province. As a matter of rain, winter is at the top and after that autumn and spring comes. Summer has a little rain and often is a dry season. The maximum daily precipitation in Koohrang is 145 mm. The annual total average of in Koohrang station is 1414 mm. This is at the top. In other stations the amount of rain has been reported as follows: Shahrekord 319 - Borujen 245.2- Lordegan 509.6 - Dezzak 424 - Avargan 545.5 Emam Gheis 570.2 and in Zamankhan 336.9 mm.
Wind direction and speed:
Wind direction in the Chaharmahal and Bakhtiary province is usually from the west and the southwest. In the center of the province Shahrekord the wind direction are frequently the southwest in the winter and spring. Also in July and August the flow is from the East and in September and autumn is from the southwest. The annual average of the wind speed in Shahrekord is 4.1 m/s. In Lordegan – kiar and Gandoman, the flow of the wind is southwest and western. In winter the blowing of the winds is very cold. All the west part of Dopolan, Absabz and the Valley of Dopollan, the high mountains, block the strong winds. The most intense wind has been reported in this province is 20 m/s in Shahrekord, 28 m/s in koohrang 15 m/s in Lordegan and 20 m/s in Borujen.
The yearly windrose of shahrekord synoptic station
Shahrekord synoptic windrose station in spring
Shahrekord synoptic windrose station in summer
Shahrekord synoptic windrose station in autumn
Shahrekord synoptic windrose station in winter
The cloud covering:
In winter the amount of cloud in the sky is more than other seasons, like most of the parts of our country. Cloud covering in spring decrease and in summer reaches to the least. At the beginning of autumn, the cloud covering will increase againe. Among of cloud in the sky is explaining with numbers. For example 8 of 8 clarifies the complete cloud covering. If we divide the sky into 8 parts and if 6 parts of it is cloudy, we use 6/8. According to this division, a complete and perfect covering of cloud (8/8) has been reported in Shahrekord 37 days, Borujen 21 days, Lordegan 33 days and Koohrang 48 days.
The sunshine hours:
An instrument measures it. Usually the sunshine hours related to latitude, season and the amount of cloud in the sky. In Chaharmahal and Bakhtiary the average of annual sunny hours (totally) in Shahrekord is 3144 hours,and in Borujen 3377.2, in Lordegan 3171 hours and in Koohrang 3.2879 hours have been observed.
Thunderstorm:
In Shahrekord, the center of ChaharMahal va Bakhtiary, for 6 or 7 days a year, storm and Thundering is taking place. Most of them are in April and may. Koohrang, regarding to thunder and storm is at the top with 26 days a year.
Snow and rain or snowy days:
In the center of Chaharmahal va Bakhtiary in shahrekord snow with or without the rain appear in 17 days a year. Koohrang is at the top with 53 days a year. Perhaps in cold and high places, snowing is more than this, but because there is no measuring station and observer, the days of snowing haven’t been measured. Considering topographic condition of the province, which is related to Alpine mountain ridge, also a lot of high places and huge amount of snow cause flood and avalanche, which is going to be considered in regional projects and plans.
Dusty days:
Just a few dusty days of year are dusty. Shahrekord 5 days and Borujen 17 days, have been the least and the most in the province respectively. Dusty days in warm month are more than cold months, because of dry flows of the regions or local.
Charcteristics of synoptic stations
Koohrang Lordegan Borujen Shahrekord Station name
North 32-26 North 31-31 North 32-00 North 32-20 Latitude
East 50-07 East 50-48 East 51-18 East 50-51 Longitude
2285 1564 2197 2061 Elevation
Next to the tunnel 1 Inside the city Inside the city Shahrekord
airport
Position of station
Mountainous Plain Plain Plain Geographical location
of region
more more more more Climate type
Goat’s - Thorn Acorn jungle Steppe Steppe vegetation
Synoptic 1366
Climatologic 1338
Synoptic 1372
Climatology 1336
1367 1335 The year of establishment
Regional normal of the synoptic stations
Koohrang Lordegan Borujen Shahrekord Station name
1987-2000 1995-2000 1988-2000 1955-2000 Statistical period
-30.6 -21 -26.8 -32 Absolute Min. temp.
35.8 47.5 36.6 42 Absolute Max. temp.
9.2 15.3 10.5 11.8 Average of daily temp.
1414 475.8 245.2 319 Average of annual
precipitation
46 45 38 46 Average of relative
humidity
145 72 76 Daily High Tide of raining
(mm)
58 30 39 41 Max. wind speed
observed
132 113 132.2 124 Freezing days
2879.3 3296.4 3377.2 3144 Average of yearly
sunshine
47.6 33 21 37.2 Full cloudy days
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