The Iranian Plateau

Serving as a bridge between central and western asia, the Iranian plateau links the steppes of central Asia to Asia  Minor and continental Europe. It is a triangle set between  two depressions namely the Persian Gulf to the south and  the Caspian sea ,the world's largest lake,to the north. The  triangle is bounded by mountains rising round a central  depression,a desert region formed by the bed of a dried up sea.  The western mountains, the Zagros, run from northwest to  southeast and are over 620 miles in length and 120 miles in width.
Its peaks rise to between 3280 and 5570 feets and consist of  numerous paralleled folds enclosing valleys 30 to 60 miles  long and 6 to 12 miles wide.
 
The northern part of the triangle is marked by the Alborz  chain of which the highest peak ,Mount Damavand, rises to  cover 19000 feet.At its western end the Alborz reach   Azerbaijan in the center of which lies the salt lake   Urmia.To the east the Alborz chain forms the mountains of   Khorassan which are not very high , and finally the   mountains bordering the triangle are completed by a   southern chain , the Makran,and in the central part of the   plateau which is crossed by two inner mountain chains, there   is a vast desert depression which is divided into two parts: Dasht-e-Kavir to the north and Dasht-e-Loot to the south.
 
While these inner plains are rather arid ,the two outer   plains of Mazandaran to the north and Khuzistan to the   south are fertile lands with many resources that contribute   to the country's agriculture and economy.In the latter also   lies the ancient capital of Susa with easy access to   Mesopotamia and Asia Minor.

Rivers

The 850 kilometer long Karoon which is the widest river in   Iran is the country's only navigable river. It flows into   the Persian Gulf. Among other rivers that flow into the sea   of Oman and the Persian Gulf are   Karkheh,Dialeh,Jarahi,Hendijan and Arvand.
 
The rivers Arass,Sefidrood,Atrak,Taalaar and Gorgan on the   other hand are among the streams that flow into the Caspian   sea. Iran's longest river,the 1000 kilometer long   Sefidrood,which is mainly a mountain stream rises in the   Alborz mountains and irrigates the Gilan plain before   flowing into the Caspian sea. The rapid tumbling river   Haraz also rises in Mount Damavand and flows into   the Caspian sea.
 
Among the inland streams the Zayandehrood which passes   through the city of Isfahan and disappears in the Gavkhooni   swamp is the largest. The inland rivers,usually seasonal   streams,are mainly used for irrigation of farmlands across   the country. Among other inland rivers are Zarrinehrood which flows into the Lake Urmia, Siminehrood, Ajichai, Nazloochai and the Qomrood which flows  into the Hose Sultan    salt lake south of Tehran,Bampoor and  Halilrood which disappear   in the Jezmoorian swamp in Kerman province, the river Hirmand which flows into the lake Hamoon in Sistan, Rood-e-Koor which pours into the lake Bakhtegan in Fars province, and Tajan and  Kashafrood in northeastern Iran.
 

Lakes

The Caspian sea is in fact the world's largest lake. However,it is well known as a sea in every book of geography.  Having this in mind,Lake Urmia is therefor   Iran's largest lake. Located in Western Azerbaijan  province,   it  is a  lake with high salinity. Its  length is 130 kilometers and it is 50 kilometers wide in its widest point. Small passenger and cargo boats link Port Sharafkhaneh   on the east coast of the lake to Port Gelemkhaneh on the   west coast. There are also scores of other smaller harbors   by the lake.
 
Lake Urmia which is only about 20 meters deep has some   tiny islands the largest one of which is 9 kilometers long   and only 3 kilometers wide.
 
Almost all other lakes in Iran are also salt lakes. The Hose   Sultan salt lake between Tehran and the religious city of   Qom is 20 kilometers long and 15 kilometers wide and its   surface is covered with salt.
 
Lake Hamoon in Eastern Sistan province with its ever   changing water surface level, and the shallow salt lake   Bakhtegan in Fars province are among the other major lakes   of Iran.
 

  The Seas

In the south ,the sea of Oman,an extension of the Indian  Ocean,joins the Persian Gulf at the Strait of Hormuz;and on   the north ,there is the world's largest landlocked body of   water i.e. the Caspian Sea.
 
The Persian Gulf extends from the strait of Hormuz sweeping   in a northwesterly direction for 800 kilometers from the   strait of Hormuz to the Karoon River. It is between 180 and   250 kilometers wide although at the strait of Hormuz it is   only 35 kilometers across. Its area is some 250000 square   kilometers and its depth is about 100 meters at its deepest   point near the strait of Hormuz. The important islands of   the Persian gulf are Hormuz,Kish ,Kharg,Larak, and the   Greater and Lesser Tonbs.
 
The Caspian Sea,with a surface area of 170000 square miles   is 730 miles in length and from 130 to 270 miles in   width. Its salinity is far lower than that of the oceans and   it has very little ebb and flow. It is shallow in the north   while in the central and southern portions there are two   deep basins separated by a submarine ridge running from   west to east. The water level of the Caspian has been always   fluctuating due to changing climatic conditions and the   changes that have occurred in the course of some rivers that   flow into it. The Caspian is about 90 feet below sea level.
 

Climate

The mountain areas of Iran are generally characterized by  cold winters and mild summers.The air is usually dry except  for the brief rainy season.The long winter in the higher  mountain regions exceeds six months extending into the late  spring.At altitudes higher than 2000 meters above sea level  around mount Damavand minimum January temperature has been registered at -12 C. However,even a -36 C absolute lowest  temperature had been recorded in Saghez ,Kurdistan in  February 1972.In the short summers of regions like  this,maximum temperature seldom exceeds 36 C and it falls  to about 10 C at night.
 
Except at the Caspian littoral ,the lowlands are usually  characterized by dry weather,high temperature and large  daily annual temperature ranges of zero to +55 C. The  hottest points are in central or northern Khuzestan where  summer day temperature seldom falls below +45 C.
 
At the Caspian coasts temperature is moderate with low daily  and annual ranges while humidity is high and precipitation  heavy. Mean temperature in this region varies from +26 C in  the summer to +7 C in the winter.
 
The southern coastal plains are hot and humid throughout  the year. Maximum temperature in Khuzestan usually exceeds  +55 C while it is something around 38 in the usually 86%  humid Oman sea coasts. In these regions the temperature never  falls below the freezing point. Here, summers are long and  hot while winters are mild and short.
 

Rainfall

Winter and early spring are the rainy seasons of Iran ,but the annual rainfall is generally low except along the Caspian sea coasts.The amount of rainfall decreases from north to south of the country as temperature increases. The central deserts of the country have short rainy seasons which are limited to the coldest months of the year.In some desert regions the number of rainy days in a year seldom exceeds 5 or six days.
 
Summer is dry everywhere except ,again ,in the Caspian littoral.There is practically no rain in the interior deserts and lowlands but there may be occasional local rainshowers along the higher peripheries. There are also occasional summer rainfalls in the southeastern mountains,however ,this is an irregular occurrence which may happen once in every decade.
 
Mid-autumn rains usually start in many parts of the country in October. In this season the Caspian littoral gets its maximum rainfall.
 
In the winter, there are snowfalls,sometimes rather heavy, along the Alborz and Zagross regions . However,snowfalls are never serious in the southern part of the country.The snow
on the mountain caps of northern Iran usually remains until
late spring.
 
Generally speaking, Iran is a country of scant rainfalls as the annual amount of precipitation for the country as a whole averages between 300 to 350 mm of rain and snow.The average precipitation range varies from less than 10 mm in the interior deserts to more than 2000 mm in the southwestern regions of Caspian littoral.
 
Bounded on the north by the Caspian sea and the    republics of  Azerbaijan, Turkmenistan , Kazakhstan, Armenia and Russia, on the east by Afghanistan and Pakistan ,on the south
by the Persian Gulf and the Sea of Oman and on the west by Iraq and Turkey, Iran is a vast country with a total land area of 1648000 square kilometers (equal to 628000 square miles). Its area is 5 times the size of Italy,and equals to the total areas of Belgium,england,Germany ,France ,Denmark and the Netherlands altogether.
 
The country can be roughly divided into three distinct areas:one third of it consists of mountains,one third of deserts,and one third of forests.
 
On January 1, 1996 the temprature in Ardabil was 23 degrees centigrade below zero while it was 28 degrees above zero in Siri Island in the Persian Gulf. Quite a difference! In fact the country is so large and its climatic conditions are so varied that when some people are skiing at the Alborz slopes ,others can swim in the hot waters of the Persian Gulf ,and when frostflowers bloom in Azerbaijan,beautiful palm trees cast their long shadows on the enchanting plains of Khuzistan,while at the same time colorful rose gardens mark the spring in Shiraz.