geographic north
2.The location of the North geographic pole wanders in a small erratic circle-like path called the Chandler wobble.
3.Based on an analysis of causes and basic characteristics of drought in north and south areas of China, it is pointed out that drought in north areas, such as the Yellow River Basin and the Huaihe River Basin, was characterized by the severe systematic demand-supply contradiction resulted from the shortage of water resources, and successive drought disasters intensified by hot and dry weather, and that drought in south areas was characterized by the occurrence or successive occurrence of dry years due to hot and dry weather and the seasonal water shortage induced by their geographic and climatic features and insufficient water supply capacity.
4.2) The main geographical elements of the exotic weed genera were Cosmopolitan,Pantropic,North Temperate,Tropical Asia & Tropical America disjuncted,Old World Temperate,accounting for 39.47%,21.05%,18.42%,13.16% of the total respectively(excluding cosmopolitan). Compared with the flora geographic elements of Mount Bei in Jinhua,higher tropical proportion was found in alien weed,and special attention should be paid to species with Tropical Asia & Tropical America disjuncted distribution pattern;
