Flying through turbulence can be stressful and fatiguing, so it's good to understand where and how it happens. Here are the 7 most common types of turbulence:

1) Clear Air Turbulence

CAT normally occurs outside of clouds at altitudes above 15,000 feet MSL, and its caused by strong wind shears in the jet stream.

2) Thermal Turbulence

Localized columns of convective current (picture a rising column of warm air) result from surface heating or cold air moving over warmer ground. For every rising current, there is a compensating downward current usually slower in speed, since it covers a broader area, causing turbulence.

3) Temperature Inversion Turbulence

Even though a temperature inversion produces a stable atmosphere, inversions can cause turbulence at the boundary between the inversion layer and the surrounding atmosphere.

4) Mechanical Turbulence

When the air near the surface of the Earth flows over obstructions, such as bluffs, hills, mountains, or buildings, the normal horizontal wind flow is disturbed and transformed into a complicated pattern of eddies and other irregular air movements.

5) Frontal Turbulence

Frontal turbulence is caused by lifting of warm air, a frontal surface leading to instability, or the abrupt wind shift between the warm and cold air masses. The most severe cases of frontal turbulence are generally associated with fast-moving cold fronts.

6) Mountain Wave Turbulence

As air flows over the tops of mountains, traveling down the leeward side, a standing mountain wave is formed and air currents oscillate between altitudes. Mountain waves and turbulence can extend for hundreds of miles downwind of the mountain range.

(Here's what mountain wave can look like from the flight deck...)

7) Thunderstorm Turbulence

The storm cloud is only the visible portion of a turbulent system in a thunderstorm. But updrafts and downdrafts often extend outside the storm, with severe turbulence possible as much as 15 to 30 miles downwind.