Refers to areas of the Earth that have similar temperatures. The major zones are hot, temperate and polar and are roughly demarcated by lines of latitude. Within each zone there are different climates, because of the effects of the distribution of continents and oceans and the circulation patterns of the atmosphere and oceans. For example, Adelaide and Sydney are on almost the same line of latitude but, while Adelaide has a Mediterranean climate with very dry summers and moderately wet winters, Sydney has a temperate climate with wet summers and drier, but not dry, winters.