Aviation Weather Understand basic facts and general principles of aviation weather. • Explain the weather hazards associated with aviation. • List the types of severe weather that affect aviation.
Weather Hazards • Reduced Visibility • Three miles lateral visibility is acceptable for safe flight under visual flight rules (VFR). • Possibility for accidents is greatest when visibility is reduced • Clouds, rain, snow, fog, and obstructions. • Haze and smoke can reduce visibility when the wind is calm.
Weather Hazards • Icing • Ice is present in the atmosphere at all times-15,000 feet in summer and as low as 1,000 feet in winter. • Glaze and Rime ice form on an airplane’s windshield, its propeller, and other aerodynamic surfaces. • Glaze ice is formed and builds quickly as an airplane flies through super-cooled rain droplets.
Weather Hazards • Icing • Rimeice also forms when an airplane is flying through super-cooled cloud condensation. • Frost disturbs airflow to reduce lift efficiency. • Larger, more sophisticated aircraft are equipped to break or melt ice as it is formed.
Severe Weather • The NWS severe weather classifications are based upon destructive effects with regard to surface cultural features.
Severe Weather • Thunderstorms • A storm accompanied by thunder and lightning. • A Thunderstorm is local in nature and is always produced by the growth of a cumulus cloud via convection • Three stages • Cumulus • Mature • Dissipating
Severe Weather • Thunderstorms - Cumulus Stage (Early Stage)
Severe Weather • Thunderstorms - Mature Stage (Developed Stage)
Severe Weather • Thunderstorms - Dissipating Stage (Dying Stage)
Severe Weather • Tornadoes • Local storm that focuses destructive forces on a small area. • Generally occurs with severe thunderstorms. • Destructiveness caused by high winds and very low pressure that gives the tornado incredible suction
Severe Weather • Hurricanes • A strong tropical cyclone with winds that surpass 100 mph. • A large revolving storm with a calm center (eye).
Severe Weather • Hurricanes • Born over the tropical water of the Atlantic and Pacific Oceans, the Gulf of Mexico and the Caribbean Sea. • Energy gained from heat given off by warm air.
Severe Weather • Hurricanes • Tropical depression • Tropical storm • Hurricane
Severe Weather • Hail • May be within a strong cumulus cloud before any type of precipitation falls to the surface. • The combined velocity of an aircraft and hail gives these small pellets a tremendous amount of energy.
Severe Weather • Hail • Encounters with larger hail are even more damaging. Hail having the size, weight, produced by thunderstorms can rip a small plane apart. • Hail and rain pulled into an aircraft engine can cause the engines to stall and flame out, as well as cause internal damage.
Summary 1. Weather Hazards 2. Severe Weather