CLOUD volume is an essential component of weather forecasting, but for decades meteorologists have been frustrated in their attempts to measure it. Now Canadian researchers have developed a formula to estimate the size of any cloud. It could have a profound impact on short-term weather forecasts and our understanding of the role clouds play in global warming.
Satellites can only measure the length and breadth of clouds, and researchers rely on weather balloons to assess their depth. But the measurements are inaccurate because balloons, blown around by winds, rarely fly in straight lines. This forces meteorologists to work from two-dimensional measurements. 鈥淭he assumption that clouds are flat vastly reduces our forecasting capability,鈥� says Shaun Lovejoy, a physicist at McGill University in Montreal.
His team initiated the largest-ever study of clouds, using an aircraft-mounted laser device capable of measuring cloud size, speed and composition. They collected nearly a thousand times more data than any previous comparable experiment, and created a formula that defines how the depth of any cloud varies as a function of its type, length and breadth. 鈥溞影稍磗 can now estimate the parameters of all clouds, from the largest cyclone to the smallest puff of a car exhaust,鈥� says Lovejoy.
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But it will take time to modify climate models. 鈥淢odelling cloud behaviour in three dimensions requires some pretty lofty mathematics,鈥� says Lovejoy.