the eastern portion of the city, there lies a small area of low mountains, with the Laodaodong Mountain, which has an altitude of 711 meters, being the highest. The city is also situated at the crisscross point of the third east–westward "Europe-Asia Continental Bridge". Changchun prefecture is dotted with 222 rivers and lakes. The Yitong River, a small tributary of the Songhua River, runs through the city proper. Climate Changchun has a four-season, monsoon-influenced, humid continental climate (Köppen Dwa). Winters are long (lasting from November to March), cold, and windy, but dry, due to the influence of the Siberian anticyclone, with a January mean temperature of . Spring and autumn are somewhat short transitional periods, with some precipitation, but are usually dry and windy. Summers are hot and humid, with a prevailing southeasterly wind due to the East Asian monsoon; July averages . Snow is usually light during the winter, and annual rainfall is heavily concentrated from June to August. With monthly percent possible sunshine ranging from 47 percent in July to 66 percent in January and February, a typical year will see around 2,617 hours of sunshine, and a frost-free period of 140 to 150 days. Extreme temperatures have ranged from to . Administrative divisions The sub-provincial city of Changchun has direct jurisdiction over 7 districts, 3 county-level cities and 1 County: Demographics According to the Sixth China Census, the total population of the City of Changchun reached 7.677 million in 2010. The statistics in 2011 estimated the total population to be 7.59 million. The birth rate was 6.08 per thousand and the death rate was 5.51 per thousand. The urban area had a population of 3.53 million people. In 2010 the sex ratio of the city population was 102.10 males to 100 females. Ethnic groups As in most of Northeastern China the ethnic makeup of Changchun is predominantly Han nationality (96.57 percent), with several other minority nationalities. Culture Dialect The most commonly spoken dialect in Changchun is the Northeastern Mandarin, which is originated from the mix of several languages spoken by immigrants from Hebei and Shandong. Then, after the PRC was established, the rapid economic growth in Changchun attracted a huge amount of immigrants from various places, so the northeastern dialect spoken in urban areas of Changchun is closer to the Mandarin Chinese than the in rural areas because the immigrants had a great impact on the northeastern