The descriptive abbreviations and classification introduced by the International Meteorological Congress, held at Munich in 1891, is that which is now adopted more or less completely by all the national weather bureaus. Systematic observations upon the heights and movements of all clouds were made at many stations throughout the world in concert from May 1, 1896, to July 1, 1897. From these observations a general idea of the heights of the respective kinds of clouds may be gathered, as shown in the preceding list, compiled from Professor Bigelow's Report on International Cloudwork of the United States Weather Burcau, page 20. The titles and descriptions of the clouds are as used by the International Committee.

CIRRUS (Ci.). Isolated feathery clouds of fine fibrous texture, generally brilliant white, frequently arranged in bands which spread like the meridians on a celestial globe over a part of the sky, and converge in perspective toward one or two opposite points of the horizon. (In the formation of such bands, cirro-stratus and cirrocumulus often take part.)

CIRRO-STRATUS (Ci. S.). Fine whitish veil, sometimes quite diffuse, giving a whitish appearance to the sky, and called by many 'cirrus haze,' and sometimes of more or less distinct structure, exhibiting tangled fibres. The veil often produces halos around the sun and moon when seen through it.

CIRRO-CUMULUS (Ci. Cu.). Fleecy cloud. Small white balls and wisps, without shadows, or with very faint shadows, which are arranged in groups and often in rows.

ALTO-CUMULUS (A. Cu.). Dense fleecy cloud. Larger whitish or grayish balls, with shaded portions, grouped in flocks or rows, frequently so close together that their edges meet. The different balls are generally larger and more compact (passing into strato-cumulus) toward the centre of the group, and more delicate and wispy (passing into cirro - cumulus) on its edges. They are very frequently arranged in lines in one or two directions.

ALTO-STRATUS (4. S.). Thick veil of a gray or bluish color, exhibiting in the vicinity of the sun and moon a brighter portion, which, without causing halos, may produce coronæ. This form shows gradual transitions to cirro-stratus; but, according to the measurements made at Upsala, was of only half the altitude.

STRATO-CUMULUS (S. Cu.). Large balls or rolls of dark cloud, which frequently cover the whole sky, especially in winter, and give it at times an undulated appearance. The stratum of strato-cumulus is usually not very thick, and blue sky often appears in the breaks through it. Between this form and the alto-cumulus all possible gradations are found. It is distinguished from nimbus by the ball-like or rolled form, and because it does not tend to bring rain.

NIMBUS (N.). Rain-clouds. Dense masses of dark. formless clouds, with ragged edges, from which generally continuous rain or snow is falling. Through the breaks in these clouds there is almost always seen a higher sheet of cirro stratus or alto-stratus. If the mass of nimbus is torn up into small patches, or if low fragments of cloud are floating much below a great nimbus, they may be called fracto-nimbus (the 'scud' of the sailors).

CUMULUS (Cu.). Woolpack clouds. Thick clouds, whose summits are domes with protuberances, but whose bases are flat. These clouds appear to form in a diurnal ascensional movement, which is almost always apparent. When the cloud is opposite the sun, the surfaces which are usually seen by the observer are more brilliant than the edges of the protuberances. When the illumination comes from the side, this cloud shows a strong actual shadow; on the sunny side of the sky, however, it appears dark, with bright edges. The true cumulus shows a 'sharp border above and below. If often torn by strong winds, the detached parts (fractocumulus) present continual changes.

CUMULO-NIMBUS (Cu. N.). Thunder-cloud; shower-cloud. Heavy masses of clouds, rising like mountains, towers, or anvils, generally surrounded at the top by a veil or screen of fibrous texture ('false cirrus'), and below by nimbuslike masses of cloud. From their base generally fall local showers of rain or snow, and sometimes hail or sleet. The upper edges are either of compact, cumulus-like outline, and form massive summits, surrounded by delicate false cirrus, or the edges themselves are drawn out into cirrus-like filaments. This last form is most common in 'spring showers.' The front of thunder-storm clouds of wide extent sometimes shows a great arch stretching across a portion of the sky, which is uniformly lighter in color.

STRATUS (S). 'Lifted fog' in a horizontal stratum. When this stratum is torn by the wind or by mountain summits into irregular fragments, they may be called fracto-stratus.

In general, the cirrus, cirro-stratus, and cirrocumulus are the highest and swiftest; the altostratus, altocumulus, stratocumulus, and cumulo-nimbus are median; the nimbus, cumulus, and stratus are lowest and slowest. These three groups are also generally distinctive as to their appearances and methods of formation.

There are some rarer forms of clouds that have received special or local names, such as the following: Phosphorescent, sometimes called iridescent, opalescent, or luminous night clouds. These are seen even at midnight in Europe as distant, pure white clouds, near the horizon. Measurements appear to show that they are from 10 to 20 miles above sea-level; they may possibly be self-luminous or phosphorescent, but it is more likely that they shine by reflecting the light from a distant twilight. Hoods, or false cirri, enveloping a mountain-top, or the summit of a cumulus dome. These are formed in the air that is pushing upward over the obstructing mountain. The tablecloth of Table Mountain at Cape Town is formed somewhat like the hood, but covers the whole flat top of the mountain and hangs down a little way over the leeward cliffs with frayed edges as the cloudmatter evaporates back into invisible moisture.

The helm-cloud and helm-bar are stationary clouds, formed at the summits of standing waves of air. When an east wind blows over the Crossfell Range, in Cumberland, England, there is formed not merely a cloud or hood or helmet with rain at the summit of the range, but a series of undulations to the leeward, one or more of which may rise high enough as a standing wave to form a cloud at its summit; through this cloud, in fact, the wind is blowing, and the cloud-particles formed on the windward side are

carried up through the cloud and down again on the leeward side, evaporating and disappearing as they descend at about the same level as when they were formed on the windward side. Tornado cloud and waterspout cloud are the distinctive, cloud-like form that reaches down nearly to the surface of the earth or ocean from the main cloud-mass above, and marks the central axis of a whirling mass of air. Within such a whirl, the barometric pressure is reduced by reason of centrifugal force, and any air that is drawn inward expands, cools, and forms cloud, just as it would do if it rose upward into regions of lower pressure. When the whirl ceases, the cloud immediately disappears. Globo-cirrus, a cirrus cloud having a globular form, from which stream downward fibres or filaments, as though the particles of the globular mass were being pulled out by the wind, or were settling down by their own weight into air-currents of a different velocity horizontal. Mammato-cumulus, protuberances or pockets on the under side of an otherwise flat-bottomed cloud, as though the heavier portions of the cloud were settling down in groups from the main cloud.

The study of the movements of the clouds is

Con

our principal source of information relative to the general motion of the air at considerable heights above the sea or land. During the past fifty years an increasing amount of attention has been given to this matter, and the use of the nephoscope and photogram-meter has greatly in creased the accuracy of observation. By international agreement, special observations were made in many countries in 1896 and 1897, the results of which were published in 1898-1901; of these reports the most important is that by Prof. F. H. Bigelow, published in the Annual Report of Prof. Willis L. Moore, chief of the United States Weather Bureau. More recently, Prof. Hildebrandsson published a general report based on the international observations of clouds, which is translated in the Quarterly Journal of the Royal Meteorological Society for October, 1904. sult Clayden, Cloud Studies (London, 1905). The average area covered by clouds, taking the globe as a whole, is about one-half of its surface. They, therefore, play a very important part in the distribution of solar heat over the earth's surface and within the atmosphere, and the consideration of this influence alone is a very important but difficult problem in the determination of the motions of the atmosphere. See DEW; EVAPORATION; NEPHOSCOPE; RAIN; SNOW. CLOUDBERRY (ME. cloud, mass of rock, hill, AS. clūd, round mass, mass of rock berry) (Rubus chamamorus). A plant of the same genus with the dewberry, which it resembles. It has a trailing habit of growth, and never attains a height of more than 8 to 10 inches; the leaves, few, large, lobed, and somewhat kidney-shaped; the flower large and white, male and female flowers on separate plants, the female plant producing an orange-red fruit equal in size to a dewberry, and of an agreeable flavor. It is a native of the northern parts of Europe, Asia, and America. In Great Britain it is chiefly confined to elevated moors; in Norway and Sweden it is much more abundant, and the fruit is highly valued and made into excellent preserves. In America it is found only sparingly south of the Canadian boundary, but it is common and greatly prized in Newfoundland,

Labrador, Nova Scotia, and northern Quebec. It is abundant through northern Canada, extending from the Atlantic to the Pacific and north to the Arctic Circle. Unfortunately, the plant is of difficult cultivation, and no attempt to make it produce fruit freely in our gardens has yet been successful. Somewhat similar to the cloudberry is Rubus geoides, which yields a very agreeable fruit, as large as a raspberry, one of the few native fruits of Tierra del Fuego and the Falkland Islands.

CLOUDBURST. A term first applied in the United States about 1840, and in India about 1860, to a sudden extraordinarily heavy local rain. No definite rate or amount of rainfall, or area covered by it, has been assigned as a limit proper for distinguishing cloudbursts from ordinary heavy rains. Many special cases of cloudbursts have been described in English and American meteorological journals, especially in the United States Monthly Weather Review, from which it may be seen that the term is rarely used unless six or more inches of rain fall, and at the rate of 10 or more inches per hour. Thus, in one case, 10 inches fell in an hour; in another, the extreme case, 21 inches. Nothing definite is known as to the areas covered by these heavy rains; but it is not likely that the heaviest cover more than an acre, or that the lighter ones cover more than a square mile. Several cloudbursts have occurred on the castern slope of the Rocky Mountains; but the great rains that cause the heavy floods along the eastern slope of the Appalachians from Georgia to Pennsylvania sometimes attain the intense local character that is ordinarily attached to the term cloudburst. Professor Ferrel has explained how a mass of water can be held within the cloud by means of rapidly ascending currents; but there is scant evidence of the actual existence of the strong ascending wind required by this explanation, and it equally possible that cloudbursts may result from the sudden formation of a large mass of rain in a very tall cloud, rather than from the gradual accumulation of rain in the clouds. Consult: Ferrel, Recent Advances in Meteorology (Washington, 1886), and his Popular Treatise on the Winds (New York, 1889).

seems

CLOUD ON TITLE. An apparent defect in the title to real estate, based on a written instrument, judgment, or order of court, which purports to create an interest or lien in or an incumbrance upon the land in question. The person whose land is so affected may have the 'cloud' removed by appropriate proceeding in equity, instituted by a bill in the nature of a bill to quiet possession, known specifically as a bill to remove cloud on title.' The judgment of the court may direct the obnoxious instrument to be delivered up and canceled, or the record of such incumbrance or lien canceled, or may by decree declare a judgment, order of court, or proceedings under an invalid tax-levy, to be void and of no effect so far as the land in question is concerned.

In order to obtain this remedy, however, the instrument or act purporting to create the cloud on title must have apparent validity. A deed or mortgage void upon its face does not create a cloud, and cannot be attacked by such a proceeding. See BILL IN EQUITY; INCUMBRANCE;