7. Nimbus (N.), Rain Cloud.—A thick layer of dark clouds, without shape and with ragged edges, from which continued rain or snow generally falls. Through openings in these clouds an upper layer of cirro-stratus or alto-stratus may almost invariably be seen. If the layer of nimbus separates up into shreds, or if small loose clouds are visible floating at a low level, underneath a large nimbus they may be described as fracto-nimbus (Scud of sailors). See fig. 9.
8. Cumulus (Cu.) (Wool-pack Clouds).—Thick clouds of which the upper surface is dome-shaped and exhibits protuberances while the base is horizontal. These clouds appear to be formed by a diurnal ascensional movement which is almost always observable. When the cloud is opposite the sun, the surfaces usually presented to the observer have a greater brilliance than the margins of the protuberances. When the light falls aslant, these clouds give deep shadows, but if they are on the same side as the sun they appear dark, with bright edges. See fig. 7.
The true cumulus has clear superior and inferior limits. It is often broken up by strong winds, and the detached portions undergo continual changes. These altered forms may be distinguished by the name of Fracto-cumulus.
9. Cumulo-nimbus (Cu.-N.); The Thunder-cloud; Shower-cloud.—Heavy masses of clouds, rising in the form of mountains, turrets or anvils, generally having a sheet or screen of fibrous appearance above (false cirrus) and underneath, a mass of cloud similar to nimbus. From the base there generally fall local showers of rain or snow (occasionally hail or soft hail). Sometimes the upper edges have the compact form of cumulus, rising into massive peaks round which the delicate false cirrus floats, and sometimes the edges themselves separate into a fringe of filaments similar to that of cirrus. This last form is particularly common in spring showers. See fig. 10.
The front of thunderclouds of wide extent frequently presents the form of a large bow spread over a portion of the sky which is uniformly brighter in colour.
10. Stratus (S.).—A horizontal sheet of lifted fog. When this sheet is broken up into irregular shreds by the wind, or by the summits of mountains, it may be distinguished by the name of Fracto-stratus. See fig. 8.
The scheme also provides that where a stratus or nimbus takes a lumpy form, this fact shall be described by the adjective cumuliformis, and if its base shows downward projecting bosses the word mammato is prefixed.
Issued as it has been with the authority of an international congress of specialists, this scheme has been generally accepted, and must be regarded as the orthodox system, and for the great majority of observations it is quite detailed enough. But it does not give universal satisfaction. Cirrus clouds, for instance, exhibit many forms, and these so diverse that they must be due to very different causes. Hence for the minuter study of cloud forms a more elaborate scheme is still needed.
Hence in 1896 H. H. Clayton of the Blue Hill observatory, Massachusetts, published in the Annals of the astronomical observatory of Harvard College a highly detailed scheme in which the International types and a number of subdivisions were grouped under four classes—stratiforms or sheet clouds; cumuliforms or woolpack clouds; flocciforms, including strato-cumulus, alto-cumulus and cirro-cumulus; and cirriforms or hairy clouds. The International terms are embodied and the special varieties are distinguished by the use of prefixes such as tracto-cirrus or cirrus bands, grano-cirro-cumulus or granular cirrus, &c.
Again in 1904 F. L. Obenbach of the Cleveland observatory devised a different system, published in the annual report, in which the International types are preserved, but each is subdivided into a number of species. In the absence of any atlas to define the precise meaning of the descriptions given, neither of these American schemes has come into general use.
Further proposals were put forward by A. W. Clayden in Cloud Studies (1905). His scheme accepts the whole of the International names which he regards as the cloud genera, and suggests specific Latin names for the chief varieties, accompanying the descriptions by photographs. The proposed scheme is as follows.
| Genus. | Species. | |
| Cirrus | Cirro-nebula | Cirrus haze. |
| Cirro-filum | Thread cirrus. | |
| Cirrus Excelsus | High Cirrus | |
| Cirrus Ventosus | Windy Cirrus | |
| Cirrus Nebulosus | Hazy Cirrus | |
| Cirrus Caudatus | Tailed Cirrus | |
| Cirrus Vittatus | Ribbon Cirrus | |
| Cirrus Inconstans | Change Cirrus | |
| Cirrus Communis | Common Cirrus | |
| Cirro-stratus | Communis | Common Ci. S. |
| Nebulosus | Hazy Ci. S. | |
| Vittatus | Ribbon Ci. S. | |
| Cumulosus | Flocculent Ci.-S. | |
| Cirro-cumulus | Cirro-macula | Speckle cloud. |
| Nebulosus | Hazy Ci. cu. | |
| Alto-clouds | Alto-stratus | |
| Alto-stratus maculosus | Mackerel sky. | |
| Alto-stratus fractus | ||
| Alto-strato-cumulus | ||
| Alto-cumulus informis | ||
| Alto-cumulus nebulosus | ||
| Alto-clouds | Alto-cumulus castellatus | Turret cloud. |
| Alto-cumulus glomeratus | High ball cumulus. | |
| Alto-cumulus communis | ||
| Alto-cumulus stratiformis | Flat alto-cum. | |
| Stratus | Stratus maculosus | |
| Stratus maculosus radius | Roll cloud. | |
| Stratus maculosus lenticularis | Fall cloud. | |
| Strato-cumulus | ||
| Cumulus | Cumulus minor | Small cumulus. |
| Cumulus major | Large cumulus. | |
| Cumulo-nimbus | Storm cloud. |
The term nimbus is to be applied to any cloud from which rain is falling, but if the true form of the cloud is visible the term should be used as a qualifying adjective. The prefix fracto- or the adjective fractus should be used when the cloud is undergoing disintegration or appears ragged or broken. Mammato- is used in the ordinary sense, and finally undatus or waved is to be added to the name of any cloud showing a wave-like or rippled structure. (A. W. C.)
CLOUDBERRY, Rubus Chamaemorus, a low-growing creeping herbaceous plant, with stem not prickly, and with simple obtusely lobed leaves and solitary white flowers, resembling those of the blackberry, but larger—one inch across,—and with stamens and pistils on different plants. The orange-yellow fruit is about half an inch long and consists of a few large drupes with a pleasant flavour. The plant occurs in the mountainous parts of Great Britain, and is widely distributed through the more northerly portions of both hemispheres. In northern Denmark and Sweden the fruit is gathered in large quantities and sold in the markets.
CLOUD-BURST, a sudden and violent storm of rain. The name probably originated from the idea that the clouds were solid masses full of water that occasionally burst with disastrous results. A whirlwind passing over the sea sometimes carries the water upwards in a whirling vortex; passing over the land its motion is checked and a deluge of water falls. Occasionally on high lands far from the sea violent storms occur, with rain that seems to descend in sheets, sweeping away bridges and culverts and tearing up roads and streets, being due to great and rapid condensation and vortical whirling of the resulting heavy clouds (see Meteorology).
CLOUDED LEOPARD (Felis nebulosa or macroscelis), a large arboreal cat from the forests of south-east Asia, Sumatra, Java, Borneo and Formosa. This cat, often called the clouded tiger, is beautifully marked, and has an elongated head and body, long tail and rather short limbs. The canine teeth are proportionately longer than in any other living cat. Little is known of the habits of the clouded leopard, but it preys on small mammals and birds, and rarely comes to the ground. The native Malay name is Arimaudahan (“tree-tiger”). The species is nearly related to the small Indian marbled cat (F. marmorata), and Fontaniers cat (F. tristis) of Central Asia. (R. L.*)
CLOUET, FRANÇOIS French miniature painter. The earliest reference to him is the document dated December 1541 (see Clouet, Jean), in which the king renounces for the
benefit of the artist his father’s estate which had escheated to the crown as the estate of a foreigner. In it the younger Janet is said to have “followed his father very closely in the science of his art.” Like his father, he held the office of groom of the chamber and painter in ordinary to the king, and so far as salary is concerned, he started where his father left off. A long list of drawings contains those which are attributed to this artist, but we still lack perfect certainty about his works. There is, however, more to go upon than there was in the case of his father,
