四年周期

Since the Holocene, ancient climate has four times: Boreal period, Atlantic period, Sub Boreal period and Sub-Atlantic, which have about 25003000 years cycle.

全新世以来，古气候发展有四个主要阶段，并具有25003000年的周期，先后分别是前北方期－北方期、大西洋期、亚北方期、亚大西洋期。

On the other hand, the more important thing is because the urban housing is a kind of heterogeneity products.

另一方面，更重要的是由于城市住房是一种异质性产品。

Climate histogram is the fall that collects place measure calm value, cent serves as cross axle for a few equal interval, the area that the frequency that the value appears according to place is accumulated and becomes will be determined inside each interval, discharge the graph that rise with post, also be called histogram.

气候直方图是将所收集的降水量测定值，分为几个相等的区间作为横轴，并将各区间内所测定值依所出现的次数累积而成的面积，用柱子排起来的图形，也叫做柱状图。