How atmospheric dryness limits increases in typhoon rainfall
Under global warming, scientists have widely expected tropical cyclones (including typhoons and hurricanes) to bring more intense and frequent rainfall. The underlying physics seems intuitive: Rising temperatures allow the atmosphere to hold more moisture, which, combined with intensifying storms, should theoretically trigger more destructive downpours. However, when researchers analyze climate…
A recent study published in Nature Geoscience has uncovered a key factor influencing the relationship between atmospheric dryness and tropical cyclone rainfall. Contrary to expectations, increasing atmospheric dryness due to global warming appears to suppress rainfall, rather than enhance it, as previously believed. This finding, led by researchers from the University of Hong Kong and Imperial College London, offers a crucial explanation for the discrepancy between projected rainfall increases in climate models and traditional theoretical calculations.
The study reveals that as the atmosphere warms, its capacity to hold moisture grows exponentially, yet the gap to complete saturation widens, leading to drier air. This dryness affects rainfall efficiency, or the ability of moisture to be converted into rain, ultimately offsetting the rainfall increases driven by storm intensification.
The research underscores the importance of considering both storm intensity and atmospheric dryness in projections of future tropical cyclone precipitation and associated flood risks.
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