Chapter summary

This chapter gives an overview of the various climates found on Earth at the macroscale, mesoscale, and microscale. Macroclimate is the large-scale climate over 2000 km or more resulting from geographic variation in net radiation, the resultant transport of heat by the atmosphere and oceans, and high and low surface pressure belts. Macroclimate zones are often distinguished based on temperature and precipitation. One such classification scheme is that of Köppen, which illustrates the major climate zones found on Earth. In contrast, mesoclimates and microclimates are regional and local climates, respectively. Microclimates are climatic features typically smaller than 2 km. A forest has a different microclimate than an adjacent clearing. Mesoscale is between microscale and macroscale, covering atmospheric processes at scales of 2–2000 km. Regional (mesoscale) climates are illustrated in terms of the effect of topography on solar radiation, temperature, and precipitation in mountains. Lakes and oceans also greatly influence local and regional climate, with generally mild temperatures and reduced temperature variability compared with inland climates. Differential heating between land and ocean also results in a local circulation known as a sea breeze.

Global climate zones

Although no two places experience exactly the same climate, several different generalized climate zones can be recognized. Figure 2.1 (color plate) illustrates one such climate classification – the Köppen classification as modified by Trewartha (Finch et al. 1957; Trewartha 1968; Ahrens 1998). This scheme utilizes five major climate zones based on temperature and precipitation.