CLIMATE AND WEATHER IN BASIC PHYSICAL CONCEPTS

The Earth continually receives energy from the Sun. If there was not something to balance this incoming energy then the Earth would always be heating up. The Earth, however, emits energy out into space, often called ter­restrial energy, so it loses heat. One might expect that the outgoing energy at each location on the globe would have to exactly match that coming in, in order to maintain a balance, however, observations show that this is not the case. The latitudinal distribution of solar energy reveals that it is highest at the equator and then declines to a minimum at the poles. On an annual average the equator receives a round 2.5 times as much energy from the Sun as the poles. Terrestrial radiation on the other hand is much more evenly dis­tributed. At low latitudes, between 35° S and 40° N there is an excess of incoming energy and pole wards of these latitudes there is a deficit. If there was nothing else, the low latitudes would be continually heating up and the polar region would be cooling. This is not the case and there is no overall heating or cooling. Therefore the energy lost ii balanced by energy gained. This is tailed thermal equilibrium. The Earth achieves this thermal equilibrium through the atmosphere and oceans. In response to the energy imbalance, atmospheric and oceanic circulations occur which redistribute the energy from the equator to the poles. It is the measurement of these circulations that define and quantify the weather and climate of a location. However, many elements can modify these large-scale circulations: the top­ography, the vegetation, and the land surface; these too require consideration.

The climate and weather are the result of complex interactions between components which together form (and define) the climate system. These components are the atmosphere, hydrosphere, cryosphere (frozen water), biosphere and lithosphere. Weather is usually defined as the condition of the atmosphere at a particular location at a particular time. Climate is sometimes loosely defined as the average weather sons for that success.


One is out fear of economic recession and another is the skill with which the scientific uncertainty that surrounds the problem has been highlighted. The science has been interpreted so serve a range of vested interests and the disparity between the different messages presents a confused image of global warming to the public. Therefore it is important to understand the science of global warming and climate change so that we can appreciate the nature of the problem and the difficulties of providing scien­tific certainly This then allows us to assess the claims and counter-claims of scientist, and allow to appreciate the much wider arguments of economists, social scientists and politicians.

It has been said that global warming is the largest experiment ever under­taken by humankind. It began unintentionally, with no idea of the end result and probably no way of stopping it. The experiment involves the whole planet and will affect not just our generation but many generations to come. The task is to understand that experiment, to try and predict what will happen and estimate just how big the resulting problems might be. An experiment that involves the whole Earth and everything on it is likely to be complex; we need to build our understanding on some solid foundations.