Storm Clouds
Anvil Cloud Explained: The Flat Top of a Thunderstorm
What an anvil cloud is, why strong thunderstorms spread out near the top, and why lightning can occur far from the rain core.
Quick answer: An anvil cloud is the flat, spreading top of a mature thunderstorm where rising air hits more stable air aloft and spreads outward.
How it forms
A thunderstorm updraft rises until it reaches a stable layer near the top of the troposphere.
The cloud spreads sideways, forming an anvil shape.
Why it matters
Anvils can indicate a strong or mature thunderstorm.
Lightning can occur under or near the anvil far from heavy rain.
Safety
Do not assume you are safe because the rain core is distant.
If thunder is heard, move indoors.