East Africa is generally much drier than other tropical regions, including the Amazon and Congo rainforests. The geography of East Africa has always been thought to contribute to its dryness and susceptibility to drought. However, the exact mechanism has been unclear until now.
A research from the University of Oxford and the UK's Met Office sheds light on the important role that deep valleys play in creating arid conditions in East Africa. The study suggests that east-west river valleys, such as the Turkana Valley, channel strong winds and thus act as conduits for airborne "rivers in the sky," which direct vast amounts of water vapor from the Indian Ocean towards the Congo rainforest, rather than towards East Africa, where it is needed.
The authors of the study suggest that understanding the climate trade-offs in rainfall between different regions in Africa can help improve our ability to predict future rainfall patterns. This is especially important given the policy implications of changing climate across the continent. The Congo basin, where much of the redirected water vapor ends up, is a key biodiversity hotspot and carbon store.
Source: Oxford University