Volcanic activities have a profound influence on the earth’s landforms. Solid, liquid or gaseous materials may find their way to the surface from some deep-seated reservoir beneath. Molten magma is mobile rock that forces...
The appearance and characterstic features of landforms are greatly influenced by the underlying rock type. Softer rocks like clay and shale are worn down much faster than harder rocks like granite. The ancient rocks...
The earth’s crust is made up of various types of rocks, differing from one another in mineral content, texture, structure, colour, permeability, mode of occurrence and degree of resistance to denudation. A knowledge of...
A traveller going eastwards gains time from Greenwich until he reaches the meridian 180°E when he will be 12 hours ahead of G.M.T. Similarly in going westwards, he loses 12 hours when he reaches...
If each town were to keep the time of its own meridian, there would be much difference in local time between one town and the other. At 10.00 a.m. in Georgetown, Penang, it would...
All living things as well as the physical environment in which they live interact with one another, that is, they influence one another’s character growth and development. There is interaction between plants or animals...
Vegetation is usually described by reference to its flora or floristic (species) composition and its structural characteristics. A plant community is composed of different species of plants and different plant life forms (trees, shrubs...
Vegetation is never static; it is continually changing in composition and structure. This is because the habitat factors themselves are continually changing. Furthermore, the vegetation itself also modifies its habitat and thereby generates change...
The area of land or site occupied by a given plant or plant community is referred to as its habitat. The type of plant community or vegetation which occurs in any area depends partly,...
Vegetation refers to the community of different kinds or species of plants growing together in an area and possessing a certain general physical appearance. This physical appearance arises from (a) the relative proportions of...
Tropical Cyclones, Typhoons, Hurricanes and Tornadoes All these are different kinds of tropical cyclones. They are well-developed low-pressure systems into which violent winds blow. Typhoons occur in the China Sea; tropical cyclones in the...
Both the Fohn and Chinook winds are dry winds experienced on the leeward side of mountains when descending air becomes compressed with increased pressure. The Fohn wind is experienced in the valleys of the...
As the greater part of the globe experiences seasonal changes in temperature, it is to be expected that the pressure belts and their associated winds will also be affected. 1) On 21 June, the...
Atmospheric pressure is the most important factor influencing climate, since differences of air pressure cause air circulation or movement which in turn influence weather elements. Atmospheric pressure is the pressure or weight of the...
1) Snow: This is formed when water vapour condenses in the atmosphere at temperatures below freezing point. Then the water vapour condenses directly into ice crystals. A snowflake is a mass of ice crystals...
There are three major types of rainfall. 1) Convectional rainfall: This type of rainfall is most common in regions that are intensely heated, either during the day, as in the tropics, or in the...
The cooling of moist air and the condensation and precipitation of water are brought about either by direct contact with a cold ground or by the rising of large masses of air. When an...
As a result of evaporation from oceans and seas, water is absorbed into the air as a gas known as water vapour. The actual amount of water vapour the air can hold varies with...
When the earth revolves round the sun, it travels on an elliptical orbit at a speed of 30 km (18.5 miles) per second or 107 182 km/h (66,000 m.p.h). One complete revolution takes 365¼...
The Importance of Temperature Temperature influences the actual amount of water vapour present in the air and thus decides the moisture-carrying capacity of the air. It decides the rate of evaporation and condensation, and...