Hurricane Rain
DB: I’m Deborah Byrd.
JB: And I’m Joel Block for Earth and Sky. We visited Science City at Union Station in Kansas City, where we recorded this question:
Alex: Hi, my name is Alex, and I’m from Topeka. And my question is, why does it rain so much after hurricanes happen?
DB: Alex, moisture is the key ingredient to making a hurricane. For a hurricane to form, the lower part of the atmosphere has to be saturated with moisture. The moisture spawns clouds and thunderstorms – the building blocks of hurricanes. So hurricanes and rain go together.
JB: Not all parts of a hurricane dump rain equally. What scientists call “rain bands” are lines of thunderstorms surrounding the center or “eye” of a hurricane. They’re what give hurricanes their spiral appearance. And they’re the part of a hurricane that generally produces rain.
DB: With respect to hurricanes, big plus slow equals wet. Hurricane Charley in 2004 was powerful, but small and fast, so it dumped relatively little rain. Tropical Storm Allison in 2001 wasn’t a full-fledged hurricane. But it was big and slow, and it flooded Houston with 37 inches – almost a meter – of rain. Thanks for your question, Alex.
JB: And thanks today to the National Oceanic and Atmospheric Administration, and to the National Fish and Wildlife Foundation. We’re Block and Byrd for Earth and Sky.
Links:
National Weather Service – National Hurricane Center
Hurricane Hunters – the 53rd Weather Reconnaissance Squadron
Miami Museum of Science – Hurricane Main Menu
Federal Emergency Management Agency – Hurricane Backgrounder
Author’s Notes:
Some rain bands are wetter than others. Let’s imagine a westward-moving hurricane making landfall. As it climbs ashore, it rises, pushing its top into the high, cool upper atmosphere, where its moisture condenses into rain. Winds in its north half blow from the east, from the ocean, so the rain bands there pack a lot of rain. Winds in its south half blow from the west, from dry land. So the hurricane’s north side gets drenched, and the south side stays dry.
The following people were interviewed for today’s program. Our thanks to:
Dr. Courtney Schumacher
Assistant Professor
Department of Atmospheric Sciences
Texas A & M University
Dr. John W. Neilsen-Gammon
Professor and Texas State Climatologist
Department of Atmospheric Sciences
Texas A & M University
