Weather Words: Ash Cloud

When a volcano erupts, it’s usually the bright orange lava that’s the star of the show, however, ash clouds can be just as impressive. Ash clouds are made up of fine particles of rock, minerals and volcanic glass that are lofted sometimes as high as tens of thousands of feet into the atmosphere, on occasion, even reaching the stratosphere. These particles are usually less than two millimeters in diameter, and can have serious impacts for those impacted.

Once airborne, these ash clouds can travel hundreds or even thousands of miles, being pushed by the wind. They can disrupt air travel, harm lungs, and block sunlight. This impacts people very far away from the initial eruption.

Large eruptions, like the Mount Pinatubo volcanic eruption in 1991, ejected enough ash and sulfur dioxide into the atmosphere that it actually cooled temperatures across the globe for about two years, according to NASA. Satellites now routinely track these clouds to help with aviation warnings and monitor their movement across the globe.

Jennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.