Clear Air Turbulence (CAT) is a type of turbulence that occurs in clear skies, away from thunderstorms. It is caused by sudden changes in wind speed and direction, often near jet streams or mountain ranges. Pilots cannot see CAT on radar, making it difficult to predict. CAT can happen at any altitude but is most common at cruising levels, typically above 15,000 feet. While it can be unsettling for passengers, modern aircraft are designed to handle these conditions safely. Pilots receive training to navigate through or around areas of CAT to ensure a smooth flight experience.