The kinematic character, and the extent of both summer and winter currents, are well portrayed in charts 47 and 48 for all the south and southeast of Asia. Across the islands of Japan, it will be observed, the winds blow in opposite directions summer and winter. In Siberia the monsoon winds trend along her great rivers and valleys, generally northward in the winter and the reverse in the summer, combining in both seasons with the prevailing westerlies, due to the rotation of the earth. All the other continents have their monsoons, though less powerful than those of Asia. In the great desert of Sahara, for example, there is an ascending hot current in the summer, causing a strong indraught from the Atlantic and the Mediterranean; but this is far less intense than if its action were fortified by lofty slopes and table-lands. In winter when the Sahara cools to nearly the oceanic temperature, little monsoon effect is perceptible, and the general circulation continues unperturbed. In Australia the monsoon influence is still feebler, owing to the limited extent of the country and to the general lowness and flatness of the land. Over parts of South America, the annual ebb and flow of the atmosphere is considerable, particularly along the northeastern coast, and in the whole Amazon Valley, whose aërial currents in general conspire with the trade-winds, strengthening them materially in the southern summer, though it is less in winter when the continental temperature more nearly approximates that of the ocean. The monsoons of North America have been described in some detail by Ferrel as follows: “On the continent of North America we have monsoon influences similar to those of Asia, but not nearly so strong, because the extent of the continent, and consequently the annual range of temperature, are not so great. They are, for the most part, not sufficiently strong to completely overcome and reverse the current of the general circulation of the atmosphere, and so to produce a real monsoon, but they cause great differences between the prevailing directions of the winter and summer winds.