The word weather generally describes the day to day variations of meteorological and climatic conditions at any time at any particular place. Meteorology is the science of weather.

Climate is the weather of a certain place averaged over a certain period. Weather can change dramatically and quickly by the hour but has an average consistency over ,say, a decade. Land and sea on the equator are the least seasonal and the most consistent in weather patterns. Arctic regions have the most diverse with long periods when there is virtually no sun at all.

Roughly speaking, there are six weather 'zones' on planet earth. Two polar at north and south, two tropical on either side of the equator, and two temperate zones in between them. Most of the world's population lives in the temperate zones where the weather remains the most unpredictable. For more than a century now, man has been able to forecast weather conditions and keep accurate records. At first the study was very basic, describing the local conditions on a part time basis. Today vast technological satellite systems can scan the globe searching out every little foible of the weather conditions, and predicting with some accuracy weather movements.

Man's advance on climate prediction is now highly sophisticated and scientists are able to predict possible weather conditions for a whole season or more. Some weather comes in recognisable cycles and scientists can predict, for example, the tell-tale signs of conditions building up to a typhoon, sometimes weeks before it strikes.

Through archaeology, meteorologists have been able to trace climatic conditions for millions of years. There is abundant evidence, for example, on just when the Ice Age began and ended. There is also evidence that the biblical flood of Noah's Arc fame was a real fact.

Life itself can only exist if there is light and water. Therefore the weather is of intense importance to every living thing, humans in particular. In every area the weather controls the lifestyle of the region, as well as the flora and fauna.

The modern weather forecast is an important factor in how we pursue outdoor leisure activities and winter sport including sailing, golfing, skiing, hiking, camping, windsurfing, scuba diving and fishing. Some people rely on the weather forecast for travel planning and more and more the weather forecast is used by the ordinary public as a guide for possible tornado, tropical storm, snowstorm and hurricane warnings. The jet stream forecast can give an indication to the traveller of the arrival time of transatlantic trips.

Since the 19th century civilisation has itself had a huge impact on the climate. Deforestation in Asia and South America, for example, has dramatically changed weather patterns. Basically because trees exude oxygen which 'eats up' carbon monoxide.

Industrialisation and the burning of fossil fuels have affected the ozone layer which hitherto gave some protection from the sun. Fossil fuels create carbon monoxide which thins the 'ozone layer'. Consequently, the earth is warming up and this is affecting the' polar regions'.

In short, they are gradually melting. The melt-down is presently so miniscule that the sea levels only grow by an annual five thousandth of an inch. If the ice sheets melted completely, however, the sea level would rise by seven yards - thereby endangering the four fifths of the world's population who live in coastal areas. Global warming has consequently become one of the central issues for conservationists.

Apart from this danger, the temperate zones could well become tropical within the next century or so, making the tropics themselves almost uninhabitable.

Presently, the temperate zones enjoy four distinct seasons of approximately three months each per year. The climatic season in the northern and southern hemispheres are directly opposite so that, for example, when England is enjoying its sparse summer, it is mild winter in Australia.

It is often joked at by long - suffering English people that they can experience all four seasons in one day. In August 1975, for example, during a short heat wave there was a sudden hail storm which produced widespread flooding.

In northern Europe variations in the weather can change from village to village and sometimes even from street to street. You can set off for a picnic under azure skies only to find yourself later sheltering from a deluge. Consequently, English weather has become the butt of world-wide jokes. In reality, however, the British Isles exist almost in the exact middle of the fortieth and sixtieth parallels and all the land in those areas could have similar climatic conditions.

Wind plays an important part in global climate. Everything from a gentle sea breeze to a full scale hurricane. Although modified by local conditions there is a basic world-wide wind system conditioned by pressures of temperature. Trade winds and gulf streams in the sea play an enormous part in world weather patterns.

It is a meteorological fact that the higher the sun is in the sky, the warmer it will be. On the world's axis the equator spins directly under the sun and is consequently the hottest. Simply speaking, the further a place is from the equator, the cooler it will be. Temperatures can range from 140 centigrade on the equator to minus 50 on the poles. Both these extremes can be completely unbearable to humans.

Most of the equator crosses oceans, especially the Pacific, but parts of northern South America, central Africa and SE Asia are directly on the line. Conversely, the polar regions are so very cold that they are virtually uninhabited.

Weather, therefore, plays a vital and fundamental role in the lives of the whole world. The weather forecast in many Western countries gets more collective viewing ratings than any other single show.