A Map of Flying Weather

Abstract

Fl LYING is a term frequently encountered in aviation literature. Although it lacks a single, simple definition, the concept is of interest to the geographer as an immediate application of weather phenomena to such specific economic activities as commercial flying and the location of aircraft manufacturing plants. Likewise of interest to the geographer is the presentation of the distribution of flying weather, once it has been defined, in map form. The definition of flying weather, presumably the weather in which one does or can fly, including taking off from and returning to the surface, involves answers to the questions Who is doing the flying? and What is he flying? Obviously the possibility of flying under various conditions of weather depends on the skill and experience of the pilot, the size and type of plane, and the variety of instruments with which the plane is equipped. Many atmospheric elements are involved. Of prime importance is any condition affecting visibility: fog, cloudiness, heavy rain, snow, ice crystals, haze, smoke, and dust. Closely associated is ceiling, the distance from the surface to the lowest cloud layer reported as broken clouds or overcast. In addition the flyer must reckon with hazards that accompany strong winds, electrical storms, hailstorms, and the presence of icing conditions at normal flying altitudes. Even with the absence of the above conditions, excessive heat may influence the ease of take-off and hence the payload factor, especially for heavier planes. In the operation of jet planes in particular, high temperature and high relative humidity increase the runway length requirements. Similarly, longer take-off runs are required in the lighter air of higher altitudes. Thus elevation alone, regardless of local atmospheric conditions, must be recognized as a factor in evaluating the flying possibilities of any given locality. It is at once apparent that flying weather requires the simultaneous consideration of many variable elements, some of them difficult or even impossible to measure. The numerous factors involved preclude the likelihood that any single station will provide the perfect set of conditions for flying. Desert areas, for example, may enjoy relative freedom from atmospheric moisture affecting visibility, but often at the price of excessive surface heat, high winds, and occasional dust storms. A partial solution to the problem of differentiating flying weather may be found by employing various combinations of two of the more important elements, ceiling heights and visibilities. This has been done in Classified Flying Weather for the United States, a publication of the Weather Bureau.' As stated in the Introduction 1 Classified Flying Weather for the United States, United States Weather Bureau, Division of Climatological and Hydrological Services, Aviation Section, Washington, 1946.