Introduction

Abstract

Looking at the surface of the earth as it is today one finds that about 34% consists of continents about a tenth of which are covered by relatively shallow water (the continental shelves), the remainder being ocean. At the poles the surface is covered by permanent ice, and a large area is covered by ice and snow for half of the year. Between the Tropics there is a region where it is hot and the climate is fairly predictable. Between the Tropics and polar regions is a zone subject to much more extreme seasonal variations and unpredictable weather. In this zone are the regions that suffer the monsoon, hurricanes and cyclonic weather. The present disposition of the continents and oceans affects climate, causing some parts to be humid and others dry, some parts along west-facing coastlines are subject to little annual variation in climate, while others in the interiors suffer extremes of climate between summer and winter. Land areas vary in topography. There are mountainous belts, hilly land and flat lands, the latter either low lying near sea level or elevated.