Background Information: Climate
Climate refers to the long-term changes in atmospheric conditions including temperature, rainfall, wind, humidity, pressure and cloudiness. One would need to take into account the fact that superimposed on the arithmetical average of these parameters, there is generally experienced a seasonal oscillation, perhaps more noticeable in the higher latitudes. It is therefore necessary to take the seasonal patterns as a unit of measurement and to consider climate to be represented by the long-term average of the seasonal cycle over a number of years.
In reality, the meteorological conditions do not remain stable over long periods, and they are forever exhibiting fluctuations and disturbances about the seasonal cycle in time scales of hours and days. It is helpful to consider these short-term changes as Weather.
While acknowledging the presence of the seasonal cycle, Weather might be described as the discrepancies of atmospheric conditions from the expected seasonal situation. In similar terms, Climate might be described as the long-term statistical average of the seasonal cycles.
However, should long-term patterns of those discrepancies be verified, there is then implied a trend, or a change in climate. This might take the form of a gradual drift in temperature such as is envisaged in response to global warming in a greenhouse scenario. Alternatively, the trend might take the form of an increase in the incidence of severe weather, as for example in the frequency of occurrence of tropical cyclones. This also is a condition which might be associated by some as an indicator of global warming.
In its most simple form, one might claim the following:
- Climate is what can be expected
- Weather is what is actually experienced
- Climate Change is represented by a long-term trend in either case.
The longer the time scale, the greater the need to broaden the spatial scale of interest, since there is more likelihood of complex large-scale interactions of the world's atmosphere and ocean, snow and ice cover, the state of the land surface and its vegetation.
In the Pacific, many islands experience a hot, wet season and a cooler, drier season, but there are many short-term departures from these general themes
