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Outside: Clouds, a Weight Over Your Head

Steve Roark, Volunteer Interpreter: Cumberland Gap National Historical Park

With all the rainfall we’ve had, clouds have been pretty common of late. And when you look up at fluffy clouds suspended in the sky you naturally think they do not weigh much since they are literally floating on air.   But taken as a whole, there is a surprising amount of weight hanging up there.

Clouds are of course a large group of suspended water droplets, or ice droplets depending on their elevation.  A droplet is formed when water vapor condenses on some microscopic particle of dust, and only averages around 1/500th of an inch in diameter, small enough to be held aloft in the atmosphere.  Clouds tend to be big and so all those droplets add up.

A meteorologist named Peggy LeMone figured out the weight of a typical cumulus cloud, which are those puffy white clouds that form on sunny days and look like popcorn or cauliflower.  Since a ton is hard to visualize, LeMone compared a cloud’s weight to something more meaningful: elephants.  A typical cumulus cloud weighs around 100 elephants, each averaging around 6 tons.   Considering how many cumulus clouds you see on an average day, that’s a lot of elephants floating around.

The numbers are even more impressive for a storm cloud, the cumulonimbus type with a tall anvil shaped top and flat, dark bottom.  Those can weigh in at 200,000 elephants.  The largest storm cloud formation is one formed by a hurricane, which can pack a wallop of 40 million elephants, more than all the elephants on the planet.  Now that is a pack of pachyderms. 

When conditions are right and those cloud droplets collide and stick together enough to fall as rain, some of that weight comes down here.  For every inch of rain that falls on your average roof, the cloud dropped around 12,000 pounds of water, or two elephants worth. With all the recent rain, there has been a lot of elephants flowing down my gutters. And when you think of how many elephant’s worth of rain flows off an average Walmart parking lot (162 elephants per inch of rain), it boggles the mind. 

When you see rain as a unit of weight it is easier to understand its ability to cause a lot of damage through erosion and floods. Planning how to handle all that power when it comes your way is important, whether your building a house or a driveway. Be sure to take all those elephants into account.