AERIAL VIEWS OF CLOUDS 



The illustrations which follow have been selected to show the 

 upper surfaces of clouds as viewed from auplanes. AVhen se^n from 

 above, the clouds at lower and intermediate levels do not present 

 the same appearance as from below, hence it is not always possible, 

 from an aerial view alone, to disting^uish clouds according to the 10 

 genera in the international classification which is based on appearance 

 from the ground. There are certain characteristics, however, which 

 should be observed. 



It is desirable that airplane pilots employed on meteorological 

 work shall make a systematic stud}' of clouds from the ground as 

 well as from the air in order that the clouds may be correctly identi- 

 fied. In some instances, however, it wUl be necessary to give de- 

 scriptions in plain language \\-ithout code numbers or generic names. 



Cirrus, cirrostratus, and cirrocumulus clouds are usually above 

 the levels reached by airplane observers. "\^lien lower clouds cover 

 the sky the au'plane observer may supply valuable information as to 

 high-level clouds which are not ^'isible from the ground. Occasionally 

 the au-plane may pass tlirough cii'riform clouds composed of snow- 

 flakes or ice particles at moderate heights. In some instances ice 

 particles may be seen sparkling in the sun when the particles are too 

 wideh' separated to be ^^isible as a cloud to an observer on the ground. 

 Such conditions should be recorded. 



Clouds in the intermediate and lower levek>, when seen from 

 above, often have the appearance of a continuous horizontal layer 

 or sheet. Even when there are fahly large openings, the layer may 

 appear unbroken when viewed at a distance. Near to and below 

 the observer, the openings will be ^'isible. It is important to note 

 whether or not there are any openmgs. 



Clouds in sheets or layers nearly always exhibit a rippled or lumpy 

 surface above. The degree of roughness or turbulence should be 

 noted. It may range from a slightly rippled effect to a pronounced 

 lumpiness, \\'ith parts extendmg upward in the form of towers like 

 the upper portions of cumidus clouds. 



Sometimes a layer of clouds may be pierced by cumulus or cumulo- 

 nimbus which develops below and grows until its summit protrudes 

 above the layer. This structure shoidd be carefully distinguished 

 from the development of cumulus clouds in detached but numerous 

 masses so that their tops when A'iewed in perspective toward the 

 horizon wiU appear as a rippled or lumpy sheet. 



The height and thickness of cloud sheets are also important. 



In general, aerial observations should include notes as to the follow- 

 ing features: 



1. Date, time, and place. 



2. Cloud genera when known. 



3. Height of base. 



90 



