Ch 15 – Additional Weather Hazards

2. Ch 15 – Additional Weather Hazards

3. Ch 15 – Additional Weather Hazards • Introduction • There are a number of aviation weather hazards that do not fall clearly into any categories of the previous chapters. • The purpose of this chapter is to describe these hazards and to examine their causes and effects

4. Ch 15 – Additional Weather Hazards • Additionally, information is presented to help you anticipate their occurrence and avoid their negative effects • After you complete this chapter, you will understand such diverse phenomena as atmospheric electricity, stratospheric ozone, volcanic ash, condensation trails and whiteouts

5. Ch 15 – Additional Weather Hazards • Section A – Atmospheric Electricity • Lightning • Lightning Effects • Static Electricity • Section B – Stratospheric Ozone

6. Ch 15 – Additional Weather Hazards • Section C – Volcanic Ash • Volcanic Ash Hazards • Ash Cloud Behavior • Reports and Warnings • Section D – Condensation Trails • Section E – Miscellaneous Hazards • Whiteout • Low-Level Inversions • Runway Conditions

7. Ch 15 – Additional Weather Hazards • Section A: Atmospheric Electricity • Lightning – defined as any or all of the various forms of visible electric discharge produced by thunderstorms • Lightning Effects – lightning strikes on aircraft result in a variety of adverse effects. • Although most of them are minor, in some cases, the damage can be severe enough to result in an accident or incident. • A lightning flash can be extremely bright; • temporary blindness is not an unusual occurrence

8. Ch 15 – Additional Weather Hazards • Static Electricity – refers to the spark or point discharges that occur when the electric charge difference between the aircraft and its surroundings become large enough • St. Elmo’s fire – a corona discharge that appears as a bushy halo around some prominent edges or points on the aircraft structure and around windscreens

9. Ch 15 – Additional Weather Hazards • Section B: Stratospheric Ozone • Ozone (O3) – Aprominent feature in the lower stratosphere; • has both good and bad qualities; good qualities include its absorption of damaging UV radiation from the sun; • bad qualities include it not being good in an environment where animals, people and plants are present because it is toxic; • large quantities have an acrid smell which irritates the eyes and can cause respiratory difficulties

10. Ch 15 – Additional Weather Hazards • Section C: Volcanic Ash – consists of gases, dust and ash from a volcanic eruption and can spread around the world and remain in the stratosphere for months or longer • Volcanic Ash Hazards – when an aircraft approaches an ash cloud some distance from a volcano, the cloud is not always easy to distinguish from ordinary water or ice clouds • Ash Cloud Behavior – volcanic ash clouds are most dangerous close to the volcano when an eruption has just occurred because the ash particles are large

11. Ch 15 – Additional Weather Hazards • Reports and Warnings • Volcanic Ash Advisory Centers (VAAC) – These 9 centers have the responsibility for the preparation and worldwide dissemination of a Volcanic Ash Advisory Statement in a timely manner so that appropriate Meteorological Watch Offices (MWO) may issue SIGMETs; • VAAC in the U.S. also prepare Volcanic Ash Forecast Transport and Dispersion (VAFTAD) charts

12. Ch 15 – Additional Weather Hazards • Summary • This chapter alerted you to a variety of additional aviation weather hazards, some of which are rare and others that are more often nuisances • However, all have the potential of contributing to serious difficulties when they occur with other flight problems

13. Ch 15 – Additional Weather Hazards • Summary • Also, a few of them by themselves can create critical flight conditions (for example, lightning, volcanic ash, whiteout, and hydroplaning). • As with all weather hazards, your newly gained knowledge of their causes and of the conditions under which they occur should help you anticipate and avoid the hazards