Most of China is situated in the temperate zone. Some parts of south China are located in tropical and subtropical zones while the northern part is near the frigid zone. In north China, summers are warm and short and winters long and cold. In the tropical and subtropical south, trees and other vegetation remain green all year. The eastern coastal regions of China are warm and humid and have four distinct seasons. But the temperatures in the interior areas of northwest China change greatly during the daytime. There is a saying: "People wear fur coats in the morning and silk at noon." Because of its high elevation, the Qinghai-Tibet Plateau area, a special alpine-cold zone, has low temperatures all year round.