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This chapter describes the physical setting, biogeography, El Niño cycle and climate change effects of the coral reefs of Panama. A focus on the unique role of low diversity but complex ecological interactions, as well the importance of corals in supporting a diverse and often cryptic part of the food web is presented. Spatial and temporal variation is described as well as the potential role of human resource use and climate change on the ecosystem.

This chapter examines rainfall and associated phenomena and their possible relationship to solar activity. Rainfall can be measured directly using rain gauges or estimated by monitoring lake levels and river flows. Satellite and radar rainfall measurements have become increasingly important. Historical documentation on drought, or the absence of rain, also reveals empirical relationships. Both rainfall and evaporation show marked variations with latitude and geography. First, we examine these rainfall-associated variations and estimate how they might change with solar activity. Second, we cover empirical studies of rainfall, lake levels, river flows, and droughts. The sun bathes the Earth’s equator with enormous amounts of surface energy. Much of this absorbed radiant energy evaporates water, causes atmospheric convection, and is later released to space as thermal radiation. Steady-state energy escapes, so tropical temperatures do not rise without limit. Some absorbed energy is transported poleward by winds from the point of absorption. Intense convection near the equator leads to a large updraft known as the intratropical convergence zone (ITCZ), a band of lofty, high-precipitation clouds producing the largest rainfall of any region on Earth. Solar energy in the ITCZ is carried to high elevations where it diverges and moves poleward. It is unable to travel all the way to the poles, so instead creates a large atmospheric circulation cell known as the Hadley cell. The Hadley cell has an upward motion near the equator and downward motions at about 30° north and south latitude. These downflow regions produce clear air with few clouds and create areas of minimum rainfall called deserts. These regions of upflow and downflow are connected by poleward flows in the upper atmosphere and equatorward flows in the lower atmosphere, forming a complete circulation pattern. Outside the Hadley cell are temperate and polar regions. The temperate regions have more rainfall than the deserts, while the cold polar regions have even less precipitation. Figure 6.1 shows the three regions with relative maximum rainfall. The mean evaporation has a much simpler latitudinal variation that tends to follow the surface temperature. Figure 6.1 shows this variation as a parabolicshaped dotted line.

This chapter focuses on understanding the trade winds in the tropical Atlantic. A historical approach is taken, starting from ancient Greek and Chinese theories of wind and then discussing various later theories proposed after European exploration of the Atlantic brought the trade winds into focus. The essentially correct description was provided by George Hadley in 1735, based on the concept of momentum conservation. This chapter hence introduces crucial effects of Earth’s rotation on the atmosphere and provides an overview of tropical Atlantic wind patterns.