Aviation WeatherUnderstand basic facts and general principles of aviation weather.

1. Explain the weather hazards associated with aviation.

2. List the types of severe weather that affect aviation.

Weather HazardsReduced 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 HazardsIcing

• 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

• Rime ice 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

Severe Weather The NWS severe weather classifications are

based upon destructive effects with regard to surface cultural features.

Severe WeatherThunderstorms

• 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 WeatherThunderstorms - Cumulus Stage (Early Stage)

Severe WeatherThunderstorms - Mature Stage (Developed

Stage)

Severe WeatherThunderstorms - Dissipating Stage (Dying

Stage)

Severe WeatherTornadoes

• 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 WeatherHurricanes

• A strong tropical cyclone with winds that surpass 100 mph.• A large revolving storm with a calm center (eye).

Severe WeatherHurricanes

• 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 WeatherHurricanes

• Tropical depression• Tropical storm• Hurricane

Severe WeatherHail

• 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 WeatherHail

• 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.

Summary1. Weather Hazards2. Severe Weather