school energy&environment

A global climatic model

Man has always tried to understand the climate and make forecasts on the weather. For agricultural activities, for travel, for transportation, weather forecasts are indispensable in order to plan human activities, but also for the realization of housing, roads, bridges that must resist against the most adverse weather conditions. It is difficult for us to understand a complex system such as the climate on a planetary scale. In fact in order to understand how the climate functions and in order to build a valid and realistic model, it is necessary to understand that the climate is a complex system, a chaotic system made up of a set of orderly sub-systems. In other words, while we are able to understand the single events that take place (a thunderstorm, a snow storm, a cyclone) and to write about the physical laws governing them, we are unable to describe the behaviour of a system, where single events can be summed, using mathematical formulas. In order to describe the climate, therefore, it is necessary to elaborate models that are as similar as possible to reality, however we must be aware that any model will only be a schematic and incomplete representation of the real climatic system.
In the current climatic model it is postulated that the atmospheric circulation, and therefore  the climate on a planetary scale, depends on the differences in solar radiation  due to both orbital parameters and the Earth’s inclination on its axis during rotation. These parameters are responsible for the alternating seasons and the difference in energy between the Equator and at the Poles, and therefore atmospheric circulation is organized in six large high and low pressure cells that are also influenced by the interaction with the ocean currents. The present distribution of  the climates on the Earth and their variability during the course of the year, derive from this model.
Until significant variations in these parameters and in the physical and chemical characteristics of the atmosphere  arise, the present climatic model should theoretically remain valid without any major modifications.
However many parameters that are taken into consideration in the climatic model that is currently proposed, are difficult to control and  to foresee: and therefore, for example, small variations in solar radiation or small modifications in the oceanic circulation may produce big changes in the climatic model. The problem is to succeed in understanding whether the climatic variability that can be observed every year in different parts of the Earth, the “exceptions” to the current climatic model, are only natural and casual fluctuations, or if, instead, these are precursors of a possible change in the global climatic model.