Clouds look fluffy, but how much do they actually weigh? And how do you weigh a cloud? Clouds are composed mainly of air and millions of tiny water droplets, which form when water condenses around a “seed” particle. Seed particles can be anything from nitric acid to vapors released by trees, but they are generally very tiny. There are ways to measure the weight of a cloud.
Here is a way to measure the weight of a cloud.
Weigh the water vapor that composes it — and to do that, “you need to know something about the dimensions of the cloud,” Armin Sorooshian, a hydrologist at the University of Arizona, told Live Science. You also have to know how densely packed the droplets are. Several years ago, Margaret LeMone, an atmospheric scientist at the National Center for Atmospheric Research in Boulder, Colorado, wondered about the weight of the water in an average cumulus cloud[1].
So she did the math. First, she measured the size of a cloud’s shadow and estimated its height, assuming a roughly cubic shape. Clouds are not typically cube-shaped, but cumulus clouds are frequently about as tall as they are wide, so this assumption helped streamline the volume calculation.
Then, based on prior research, she estimated the density of water droplets at around 1/2 gram per cubic meter. “I came up with around 550 tons of water,” LeMone said. That’s approximately the weight of 100 elephants suspended above your head.
“It’s really impressive,” Soroohsian said. Of course, different types of clouds have different weights. For example, “cirrus clouds[2] are much lighter because they have far less water per unit volume,” LeMone told Live Science.
And cumulonimbus clouds[3] (the dark thunderheads you see just before a storm) tend to be much heavier. The average water droplet in a cloud is roughly 1 million times smaller than a raindrop — about the size ratio of Earth to the sun.
Footnotes
- Cumulus clouds are clouds that have flat bases and are often described as “puffy”, “cotton-like” or “fluffy” in appearance. Their name derives from the Latin cumulo-, meaning heap or pile. Cumulus clouds are low-level clouds, generally, less than 6,600 ft in altitude unless they are the more vertical cumulus congestus form. Cumulus clouds may appear by themselves, in lines, or in clusters. [Back]
- Cirrus is a genus of high clouds made of ice crystals. Cirrus clouds typically appear delicate and wispy with white strands. Cirrus are usually formed when warm, dry air rises, causing water vapor deposition onto rocky or metallic dust particles at high altitudes. Globally, they form anywhere between 13,000 and 66,000 feet above sea level, with the higher elevations usually in the tropics and the lower elevations in more polar regions. [Back]
- Cumulonimbus (from Latin cumulus, “heaped” and nimbus, “rainstorm”) is a dense, towering vertical cloud, typically forming from water vapor condensing in the lower troposphere that builds upward, carried by powerful buoyant air currents. Above the lower portions of the cumulonimbus, the water vapor becomes ice crystals, such as snow and graupel, the interaction of which can lead to hail and to lightning formation, respectively. When occurring as a thunderstorm these clouds may be referred to as thunderheads. Cumulonimbus can form alone, in clusters, or along squall lines. These clouds are capable of producing lightning and other dangerous severe weather, such as tornadoes, hazardous winds, and large hailstones. Cumulonimbus progress from overdeveloped cumulus congestus clouds and may further develop as part of a supercell. Cumulonimbus is abbreviated Cb. [Back]
Further Reading
Sources
Live Science
USGS
Science Alert
Heads Up
IFL Science
ThoughtCo.
