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Air Turbulence Causes

Air exapnds when it is heated, and it condenses when it is cooled. It rises and sinks, and its motion creates and dissipates storms. The thermodynamic properties of air are the primary reasons air moves, and when air moves in a specific manner, turbulence occurs. Geography, friction and weather patterns all affect the potential for turbulence.

Convective Turbulence
- Atmospheric convection is the vertical transport of heat and air. Convective clouds are usually billowy clouds that build upward, such as the cumulonimbus cloud. Thunderstorms form when moist surface air is heated and lifted. As it lifts, it cools and condenses; then it forms precipitation. This lifting of air around thunderstorm cells is called convective lifting, and it is a common form of turbulence. Because the mechanism of lifting that formed the thunderstorm is not just in the cloud, turbulence can exist outside the cloud as well.
Mountain Wave Turbulence
- Mountainous terrain is ripe for the occurrence of turbulence. Mountains reach thousands of feet into the atmosphere, where strong winds associated with various weather systems exist. Air that is pushed perpendicular to a mountain is lifted upward over the mountain in a motion called orographic lifting. In some instances, the air sinks on the leeward side of the mountain. If the atmosphere is unstable, precipitation occurs, but if the atmosphere is stable, the air returns to its original position. In that case, air sinks then quickly rises, causing a narrow stream of severe turbulence on the leeward side of the mountain.
Clear Air Turbulence
- Strong pressure differences cause strong air flow. Some forms of turbulence are caused by strong differences in pressure and air flow, such as may happen with the air near a jet stream. The jet stream itself is not an indicator of turbulence; however, strong wind shear, where wind speed or wind direction change abruptly over a relatively short distance, causes clear air turbulence. Because the turbulence is not associated with many visible cues, it is called clear air turbulence.
Mechanical Turbulence
- Friction causes chaos in the air. The air moving around the Earth is free and fast in the upper levels, but it can be sporadic near the surface. Buildings, hills and other obstacles force the wind to move erratically. That type of air movement causes a disruption in air flow that can create choppy turbulence known as mechanical turbulence.

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