. METEOROLOGICAL HAZARDS IN AVIATION Cpt. Ing. Naděžda Bartošová Ph.D.

1. DEFINITIONS 2. TYPES OF METEOROLOGICAL HAZARDS 3. KEY WORDS

1. DEFINITION METEOROLOGICAL HAZARDS IN AVIATION are the phenomena, that can affect the safety of the flight.

2. TYPES OF METEOROLOGICAL HAZARDS  FOG  ICING  TURBULENCE  THUNDERSTORM

FOG ● Visibility is reduced under 1 km ● Types: radiation fog (in the morning, local character) advection fog (huge, with the drizzle) frontal fog (moving with the frontal system)

ICING ● ICING IS NOT caused by ice in cloud, is caused by SUPER - COOLED liquid water droplets. ● ICING FACTORS: - LWC - Temperature (0 ;– 20) - Droplet size - Cloud type - Airfoil geometry - Airspeed - Duration of exposure

ICING ● LUQIUD WATER CONTENT : - is amout of available water, - varies from cloud to cloud, - depends on temperature

ICING ● CUMULATIVE AFFECTS OF ICING: Decreases Thrust Radio communication problems, Blockage of pitot tubes and static vents, Adverse Aerodynamic Effects.

ICING TYPES ● Clear icing - is often clear and smooth, - Supercooled water droplets, or freezing rain, strike a surface but do not freeze instantly. ● Rime icing - is rough and opaque, - formed by supercooled drops rapidly freezing on impact. ● Mixed icing is a combination of clear and rime ice. ● Frost icing is the result of water freezing on unprotected surfaces while the aircraft is stationary. ● SLD icing - Supercooled Large Droplet (SLD) conditions, - similar to clear ice.

ICING PREVENTION ● Mechanical means, which may be as simple as using a broom or brush to remove snow ● Application of Deicing fluid ● Use of infrared heating to melt and remove contaminants ● Put the aircraft into a heated hangar until snow and ice have melted ● Position aircraft towards the sun

TURBULENCE Def: Turbulence can be defined as small-scale, short-term, random and frequent changes to the velocity of air TYPES: ● Light, moderate, severe, extreme ● THERMAL above a warm surface ● MECHANICAL caused by interference of surface features on the horizontal flow of air ● SHEAR wind changes dramatically within a short horizontal or vertical distance ● AERODYNAMIC caused by an aircraft as it flys through the air (wake turbulence)

TURBULENCE THERMAL MECHANICAL SHEAR

THUNDERSTORM DEF: ● a storm caused by strong rising air currents and characterized by thunder and lightning and usually heavy rain or hail. ● formed by a process called convection, defined as the transport of heat energy TYPES: frontal non – frontal HAZARDS: ● severe turbulence, ● low level windshear, ● low ceilings and visibilities, ● hail and lightning

THUNDERSTORM 3 STAGES: Towering Cumulus Stage: - visible clouds of liquid water, - upward motion throughout the cloud, - turbulence and icing. Mature Stage: - production of precipitation, - updrafts /downdrafts motion, - turbulence, lightning, icing, microburst. Dissipating Stage: - final stage, - downdrafts, - moderate precipitation.

THUNDERSTORM STRUCTURE: Single cell Multi cell Super cell

THUNDERSTORM HAZARDS: severe turbulence, low level windshear, low ceilings and visibilities, hail and lightning

KEY WORDS  FOG - radiation/frontal/advection fog  ICING – clear/rime/mixed icing  TURBULENCE – light/moderate/severe/extreme  THUNDERSTORM - single/multi/super cell

THANK YOU FOR YOUR ATTENTION !