Radiation and Heat
Within this chapter different aspects of radiation and heat are discussed for the tropics. On a global scale the amount of annual solar radiation reaching the Earth’s surface is determined by atmospheric and astronomical factors and the average energy bud
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Contents Global Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Global Radiation Budget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heat Budget, Sensible and Latent Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Abstract
Within this chapter different aspects of radiation and heat are discussed for the tropics. On a global scale the amount of annual solar radiation reaching the Earth’s surface is determined by atmospheric and astronomical factors and the average energy budget of the Earth could be explained by the global radiation budget. Within the tropics the net radiation varies clearly across the different climatic regions. In the humid tropics the amount of net radiation shows an almost uniform annual pattern with two maxima per annum. In contrast to this, the horizontal course of the isopleths in a radiation isopleths diagram for the marginal tropics still indicates a marked diurnal cycle. At the Earth’s surface, the total incoming radiation is transformed into different heat fluxes which are either directed towards the ground or to the atmosphere. In the tropical rainforests, only 10 % of the incoming radiation reaches the ground, and only a weak flow of sensible and latent heat exists from the forest canopy towards the forest ground and vice versa. Keywords
Tropics • Radiation and Heat • Global Radiation Budget • Heat Budget • Sensible and Latent Heat T. Peters (*) Institute of Geography, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, Germany e-mail: [email protected]; [email protected] # Springer-Verlag Berlin Heidelberg 2016 L. Pancel, M. Ko¨hl (eds.), Tropical Forestry Handbook, DOI 10.1007/978-3-642-54601-3_37
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Global Radiation About 99.9 % of all energy in the Earth’s atmosphere is received from the sun and only a small fraction is produced from the Earth itself (e.g., by volcanism, by radioactive decay, or by the burning of organic materials). This energy is transported from the sun to the Earth in the form of electromagnetic radiation which is commonly known as solar radiation. Depending on its wavelength, it is referred to as shortwave radiation (wavelength is between 0.15 and 3.0 μm) or as longwave or infrared radiation (wavelengths between 3.0 and 100 μm). Temporal and spatial changes in the total amount of solar energy arriving on a horizontal surface at the top of the Earth’s atmosphere are mainly influenced by the annual changing distance from the Earth to the sun and the inclination of the Earth’s rotation axis. Over the course of the year, the average amo
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