This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Hurricanes can produce enormous amounts of rain, adding up to trillions of gallons of water. But the big risk isn't the total amount—it's how much rain falls on each location.
One town in Texas got over 60 inches (152 centimeters) of rain from Hurricane Harvey over five days in 2017. That means empty swimming pools there would have filled with rainwater 5 feet (1.5 meters) deep. Hurricane Lane dumped 58 inches (147 centimeters) of rain on Kahuna Falls, Hawaii, the following year.
So, what causes that much rain, and does the size of the storm matter? I'm an atmospheric scientist who teaches college students about weather at Georgia Tech. Let's take a look at where a hurricane's rainfall comes from and some of the questions about hurricanes and their rainfall that scientists are still trying to answer.
A few ingredients are needed for a hurricane to form: a tropical thunderstorm complex, lots of moisture in the air, winds that don't change speed much with height and warm sea surface waters below. The water temperature is very important. The magic number for surface water temperature to be able to fuel a hurricane is at least 80 degrees Fahrenheit (26.5 degrees Celsius).
At that temperature and above, the warm ocean water evaporates into the air, changing from liquid to vapor. As it makes that change, it provides energy to fuel the storm and also adds moisture to the atmosphere that eventually falls as rain. When a hurricane moves over warm water, especially when the warm water extends many feet below the surface, the storm pulls in even more energy and moisture.
This is one of the many questions about hurricanes that atmospheric scientists are working on. The average hurricane is about 300 miles (482 kilometers) wide, but hurricanes—or typhoons, as they're called in the western Pacific of the Northern Hemisphere—can be much bigger or smaller. Super Typhoon Tip in 1979 grew to half the size of the lower 48 U.S. states.
Extract — continue reading at the source.
