m the sea upon a
land area; there is a consequent retardation of the velocity of the air
currents, as the result of friction, and an ascent of the air, the
rainfall being particularly heavy where the winds have to climb over
high lands. In India, the precipitation is heaviest at the head of the
Bay of Bengal (where Cherrapunji, at the height of 4455 ft. in the Khasi
Hills, has a mean annual rainfall of between 400 and 500 in.), along the
southern base of the Himalayas (60 to 160 in.), on the bold western
coast of the peninsula (80 to 120 in. and over), and on the mountains of
Burma, (up to 160 in.). In the rain-shadow of the Western Ghats, the
Deccan often suffers from drought and famine unless the monsoon rains
are abundant and well distributed. The prevailing direction of the rainy
monsoon wind in India is south-west; on the Pacific coast of Asia, it is
south-east. This monsoon district is very large, including the Indian
Ocean, Arabian Sea, Bay of Bengal, and adjoining continental areas; the
Pacific coast of China, the Yellow and Japan seas, and numerous islands
from Borneo to Sakhalin on the north and to the Ladrone Islands on the
east. A typical temperature curve for a monsoon district is that for
Nagpur, in the Indian Deccan (fig. 7), and a typical monsoon cloudiness
curve is given in fig. 6, the maximum coming near the time of the
vertical sun, in the rainy season, and the minimum in the dry season.

In the Australian monsoon region, which reaches across New Guinea and
the Sunda Islands, and west of Australia, in the Indian Ocean, over
latitudes 0 deg.-10 deg. S., the monsoon rains come with north-west
winds in the period between November and March or April.

The general rule that eastern coasts in the tropics are the rainiest
finds exceptions in the case of the rainy western coasts in India and
other districts with similar monsoon rains. On the coast of the Gulf of
Guinea, for example, there is a small rainy monsoon area during the
summer; heavy rains fall on the seaward slopes of the Cameroon
Mountains. Goree, lat. 15 deg. N., on the coast of Senegambia, gives a
fine example of a rainy (summer) and a dry (winter) monsoon. Numerous
combinations of equatorial, trade and monsoon rainfalls are found, often
creating great complexity. The islands of the East Indian archipelago
furnish many examples of such curious complications.

4. _Mountain Climate._--In the torrid zone altitude is chiefly important
because of it