Effects on agricultural productivity

The dry tropics are characterized by a short and intense rainy season followed by a relatively long dry season. Generally the rainy season lasts from two to four months; the amount of rainfall received ranges between 400 and 1200 mm; the rainy season may have one peak (unimodal) or two peak periods of rainfall (bimodal). In the dry tropics, the rainy season is distinctly bimodal in areas lying between 5 and 12° N latitude, while it is generally unimodal in those areas located above 20° N latitude. The areas lying between 12 and 20° N show some tendency towards bimodality. The dry tropical region is also characterized by warm thermal regimes throughout the year. The annual potential evapotranspiration for most of the dry tropics ranges between 1500 and 2500 mm. The potential evapotranspiration is quite intense in the hot dry season preceding the rainy season. The US Class A open pan evaporation rates during this period range between 10 and 15 mm/day