For those who don’t like to fly, one of the worst things that could happen is turbulence. While this is normal for most flights, an extreme example is when 24 people had to be hospitalized Thursday after a JetBlue airplane hit a server batch of turbulence. For those who want to know, five facts have been provided below.

1.Turbulence is defined as “violent or unsteady movement of air or water, or of some other fluid,” according to Google.

2. There are many different reasons turbulence happens, but the most common is CAT, which stands for Clear Air Turbulence, the Telegraph reported. There are jet streams in the air that essentially control the flow of travel like water in a riverbank. When the stream ends or interacts with air that’s moving slower, it can sometimes get bumpy.

3. Sometimes it can be avoided, but that’s only if CAT is noticed by the pilot. If turbulence is going to be caused by inclement weather, the pilot can normally fly around it.

4. There are some times when turbulence cannot be avoided, like if changing the plane’s altitude means flying into another aircraft that is occupying that area or the weather is unavoidable. The pilot on JetBlue Flight 429 had to land in South Dakota after flying into two storms that were apparently unavoidable.

5. Just like with CAT, turbulence from thunderstorms cannot always be noticed. "While some turbulence can't be detected on radar, this was not that kind," Brandon Miller, a producer with CNN's World Weather team, told the publication Friday. "This turbulence was caused by the rapid rising of air inside the thunderstorms."

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