Definition
The violent, unpredictable movement of air found inside a thunderstorm and in the airspace surrounding it. Severe vertical drafts, gust fronts, and rotational currents can occur not only within the visible cloud but also for many miles outside it, including beneath the anvil, ahead of the storm in clear air, and below the cloud base where downdrafts spread outward along the ground.
Plain English
Thunderstorms throw the air around violently, both inside the storm and well outside it. The rough air can be so strong that it damages aircraft or causes loss of control, and it can be present even when the sky around the storm looks clear.
Context Anchor
Pilots encounter this term in weather training, preflight weather decisions, and in-flight thunderstorm avoidance.
Derivation
Turbulence comes from a Latin word meaning disturbance or disorder. That fits the aviation meaning: the air is not flowing smoothly, but is disturbed and changing rapidly.
Why Pilots Care
It can produce sudden loss of control, structural stress, or passenger injury, which is why thunderstorms are avoided by a wide margin.
Grounding Statement
Imagine the storm as a giant fountain pushing air violently up the middle and slamming it back down around the edges -- the rough air spreads far beyond the cloud you can see.
Intuition Check
Do not assume the air is safe just because you are outside the visible storm. Near a thunderstorm can still mean rough, dangerous air.
Example Sentence 1
The briefer warned of severe turbulence in and near thunderstorms along the route, so the flight was delayed until the line had passed.
Example Sentence 2
Even after passing the cell, the aircraft continued to feel turbulence in and near thunderstorms for another ten miles.