عنوان مقاله [English]
Intense temperature variations are not only an unfavorable phenomenon for life but have adverse effects on natural elements of structures and installations. When the temperature falls bellow certain levels, the conditions for organic activity become harsh. This level is known as temperature threshold of life. Similar thresholds can also be defined for machinery, structures and installations. Further, when the temperature falls below zero degrees centigrade, its effects on living and non-living elements of the environment are greatly enhance. The December 10th-15th 2003 cold wave killed a number of human and animals hampered the intercity as well as urban traffic. Between 70 to 75 percent of the area of the country was frozen due to penetration of an extensive cold wave on December 11th-12th 2003, for the width of low. Temperature Goveraga in Iran, ING pressure has declined considerably and the houses administrations and didactic centers warm up process has serious problems. which was resulted from a Siberian high pressure trough formed around Baikal Lake. This led to a considerable fall of temperature amounting to more than 15°C in most of the stations. A high elevation center at 500 to 700 hecto-Pascal levels formed prior to the beginning of cold wave on the Eastern Europe and moved over Caspian Sea and eastern Ukraine in the following days leading to slow down of the trough and its blockage in eastern Iran and Afghanistan, for 4-5 days, amplitude portion of country specially western half, has been affected by Rick, thus resulting in continuation of cold weather fall over Iran.