Table 113. 

 INTERNATIONAL CLOUD CLASSIFICATION. 



a. Detached clouds with rounded upper outlines {l"°^^ '^^t \wet w'eS)" 

 A. Clouds of great horizontal extent suggesting a layer or sheet ^wet weainer;. 



A. Upper Clouds, average altitude 9000". 



a. I. Cirrus. 



b. 2. Cirro-stratus. 



B. Intermediate Clouds, between 3000"' and 7000'". 



( 3. Cirro-cumulus. 

 "■ { 4. Alto-cumulus, 

 b. 5. .llto-slralus. 



C. Lower Clouds, below 2000'". 



a. 6. Stralo-cumulus. 



b. 7. Nimbus. 



D. Clouds of diurnal ascending currents. 



a. 8. Cumulus; top 1800™; base 1400"'. 



ft. g. Cumulom'uhus; top 3000" to 8ooo«>; base uoo". 



E. High Fogs, under 1000"*. 



10. Stratus. 



DEFINITIONS AND DESCRIPTIONS OF CLOUD FORMS. 



rirrus (Ci ) -Detached clouds of delicate and fibrous appearance, often showing a feather- 

 I. Cirrus (Li.). /^"'^V ™v L, roloi Cirrus clouds take the most vaned shapes, such as 

 •'■'r/:r uSs'Xn filents oflbue sky threads spreading out in the form of feathers, 

 ' n V d fihm ^ts endinHn tufts, sometimes called Cirrus uncinus, etc ; they are sometime 



S^hc opposite iSrlo. (Ci.-St. a'nd Ci.-Cu., etc., are also somet.mes arranged m 



similar bands. ) • . 1 



rirrn ^tratus (Ci -St ) —A thin, whitish sheet of clouds sometimes covering the sky 



produces halos around the Sun and Moon. 



, rirro-cumulus (Ci.-Cu.). Mackerel sky. -Small globular masses _ or white flakes 



./LS S"r-"^--«. ^cry slight shadows, arranged in groups and often in lines. 



. Alto-stratus (A.-St.). - A thick sheet of a gray or bluish color, sometimes forming a 

 4. Alto stratus ^ri. o ; structure. At other times the sheet is thin, 



compact mass of dark gray co or and «>rou^ ^^^^ ^^^^^ ^ ^e seen dimly gleaming as 



Sroug^g'rotd'gtf ThTs' ^^^^^^^^ all changes peculiar to Ci.^St., but from measure- 



ments its average altitude is found to be about one half that of Ci.-St. 



c Alto-cumulus (A.-Cu.). - Largish globular masses, white or grayish, partially shaded 

 arL^dinlZpTor lines, and often !o closely packed that ^^^«> f ^-.^/^^/.^^f/^f ' e^^ 

 S t^he^d rnLJ^r^^^^^^^l^^^ tfen^^ s 



in one or two directions. 



A Qfrnto rnnmlus (St -Cu.). — Large globular masses or rolls of dark clouds often covering 



:^:^^BF^i^^'^:^: -skymay.s.n..t^^ 

 cumuS SSLy' St. CucSurrJja^L distinguished from Nb. by their globular or 

 Sd appea?anTe a'nd by the fact that th^y are not generally associated with ram. 



. Nimbus (Nb.). Rain Clouds. - A thick layer of dark clouds without shape and with 



^' ?Ta.. from whidi 5<eac/y rain or snow usually falls. Through the opemngs m these 



cSs an uppSTayer o?cfst' or A.-St. may be seL almost invariably. If a layer of Nb. 



SMITHSONIAN TABLES. 



