This module discusses the current theories of atmospheric conditions associated with aircraft icing and applies the theories to the icing diagnosis and forecast process. The contribution of liquid water content, temperature, and droplet size parameters to icing are examined. Identification of icing type, icing severity, and the hazards associated with icing features are presented. Tools to help diagnose atmospheric processes that may be contributing to icing and the special case of supercooled large drop (SLD) icing are examined and applied in short exercises.
The use of graphics, animations, and interactive exercises in Forecasting Aviation Icing: Icing Type and Severity helps the forecaster to gain an understanding of icing processes, to identify icing hazards, and to apply diagnosis and forecast tools as aids to evaluate and anticipate potential aircraft icing threats.
The subject matter expert for this module is Dr. Marcia Politovich of
NCAR/Research Applications Program.
This module is also available in French.
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The goal of this training module is to help you improve your icing forecasts by
1. Becoming more familiar with the types, conditions, and hazards of aircraft icing.
2. Learning what factors determine icing type and severity, and how they interrelate.
3. Knowing what physical processes create favorable icing conditions.
4. Recognizing the types of mesoscale environments that generate such physical processes.
5. Learning some techniques to apply and patterns to look for when diagnosing data products for possible icing threats.
Performance Objectives
A. Aircraft Icing
1. Name and distinguish between the main types of in-flight aircraft icing; rank them in terms of potential hazard to aviation.
2. Describe the conditions under which the main types of in-flight aircraft icing form.
3. Name and distinguish between the four icing severity reporting categories used by pilots.
B. Icing Factors
1. Name the main factors that determine the type and severity of icing to expect in a given environment.
2. Identify ranges of values for liquid water content, temperature, and altitude that are most favorable to icing.
3. Describe the influence of droplet size on ice collection efficiency and accretion pattern.
4. Predict the most likely icing type and severity level to expect for given ranges of cloud liquid water content, temperature, and droplet size.
C. Icing Environments and Physical Processes
1. Describe the impact to icing of each of the six categories of water phase transitions.
2. Describe several of the most favorable synoptic and mesoscale environments for development of hazardous icing conditions:
• Three patterns that enhance cloud formation and hence icing potential
• Three environments that are especially conducive to supercooled large drop formation
• Two physical processes that support supercooled large drop formation
• Cloud-top conditions most favorable to supercooled large drop formation
D. Data Assessment
1. Assess the icing threat in various layers of skew T-log p diagrams.
2. Identify favorable areas and layers for supercooled large drop formation integrating:
• GOES 3.9 micron imagery
• Skew-T diagrams
• Profiler data
• WSR-88D reflectivity and velocity
• Surface precipitation observations
Aviation icing, airplane icing, icing type, icing severity, icing precipitation, forecasting icing, forecasting aviation icing, cloud liquid water content, droplet size, supercooled large drops, sld, rime ice, clear ice, mixed ice, warm-layer process
