Weather Words: Anvil

This segment originally appeared in today's edition of the Morning Brief newsletter. Sign up here to get weekday updates from The Weather Channel and our meteorologists.

If you ever spot an anvil on the top of a cloud, you can bet it’s a sign of maturity. But just because the cloud is mature, doesn’t mean it’s going to play nicely.

An anvil, also known as an anvil top or cumulonimbus incus (try saying that three times fast), signifies a very strong thunderstorm. You will recognize an anvil at the top of the cloud, that’s shooting out from the side of the cloud like in the image below. It has a solid appearance, therefore not wispy, with sharp, well-defined edges.

When a cloud is maturing, or growing vertically, there comes a point when the air can no longer rise, therefore the cloud begins to spread downwind, horizontally. Anvil tops are often associated with damaging winds, hail and even tornadoes. They are most definitely a sign that the storm is strong to even severe, and if you ever spot one, you should make sure you are getting weather alerts and are staying safe.

J​ennifer 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.