3106269635

Clouds on occasions exhibit features which are indicative of potentially hazardous conditions. Some of these hazardous cloud features includes:

Lenticular (lens-shaped) clouds in the lee of mountains are indicative of mountain waves and possible severe turbulence. If fhe clouds show roli or rotation characteristics they almost cerfainly are indicafive of severe turbulence.

(Courtesy K. Hayes.)

Virga, i.e. precipitation which doesn't reach the ground, provides the vi$ual clue that strong downbursts of air may be reaching the ground, alłhough they are invisible at Iow levels. These downbursts of air may cause total loss of control. (Courtesy T. Skomina.)

On occasions convective clouds display a bulbous cloud base known as mammatus. Mammatus is indicative of severe turbulence and possible imminent heavy precipitation. (Courtesy I. Forrest.)

Any funnel-shaped column descending from the base of a cloud indicates severe or exłreme turbulence. The column may take the form of a tornado, water spout or funnel cloud. (Courtesy R. Adkins.)

Reconnaissance visuelle de certaines caractćristiques de nuages h risques (tire de Wealher for General Aviation. Bureau of Meteorology. Australie, septembre 1901)

1'image que 1‘animation pour les besoins de la for-mation. L‘interactivite permetau pilote d evaluer les connaissances acquises grace aux tests d'au-tocontróle que propose le programme.

Conclusion

Les personnels des Services meteorologiques nationaux doivent absolument garder a 1'esprit 1'incidence considerable que les conditions me-

teorologiques peuvent avoir sur tous les types de vols, et sur l'aviation generale en particulier. lis doivent donc fournir des prestations adaptees aux besoins precis de cette composante impor-tante du secteur aeronautique. Les exposes ver-baux directs etant de plus en plus remplaces par des systemes automatises qui permettent de fournir 1'information meteorologique aux services de planification des vols et aux pilotes, il est

177