Clouds And The Stories They Tell

( Originally Published Early 1900's )

O, it is pleasant, with a heart at ease,
Just after sunset, or by moonlight skies,
To make the shifting clouds be what you please.

COLERIDGE, Fancy in Nubibus.

POETS interpret the moods of the clouds and put them into pleasing verse, and artists paint upon the canvas their glorious colors, while we ordinary mortals merely admire them but are powerless to give adequate expression to our sentiments. Yet, the clouds may fire our imagination until it runs riot, picturing to ourselves such forms as we wish them to reveal and making them foretell such weather as suits our fancy. To some persons clouds have no meaning and make no appeal, while to others they tell an inspiring and significant story, adding much incidental pleasure to the passing days. These joys which the clouds afford to a few are available to all who, as they walk down the avenue, are willing to observe the heavens, or in office or home muse awhile before a window which frames an alluring sky.

For centuries people have noticed that clouds are varied in form and that certain shapes are definitely associated not only with a certain type of weather but with the future weather. An old rime says :

When clouds appear like rocks and towers,
The earth's refreshed by frequent showers.

This couplet depicts an accurate observation. The "rocks and towers" are the massive billowy tops of cumulo-nimbus clouds, a summer type of convection cloud which usually begins to ac-cumulate toward noon and by mid-afternoon has established a black horizontal base from which showers fall. Sometimes, when convection becomes violent and the cloud top extends to considerable heights, two or three miles, the showers are accompanied by thunder and lightning. In fact, the public has long referred to these clouds as "thunder-heads."

Cumulo-nimbus sounds like a ponderous term intended perhaps for those steeped in the most technical aspects of the physical sciences. Except for those who are professionally engaged in studies of the atmosphere and a few who enjoy the atmospheric vagaries as a hobby, the Latin names for clouds have not come into common use. However, this does not mean that they should not. Here we may take a lesson from the lovers of flowers. When Latin was a common language, flowers were known by their Latin names, but as English acquired an important place in the world, Latin names were largely tabooed except by scientific men. However, the day of public fear of calling a flower by its Latin name is rapidly passing into history. Just ordinary folks now refer to innocent pinks as Dianthus. The Dianthus family being rather large, its members have "Sir" names, such as Barbatus, and this name in combination with Dianthus is, in plain English, nothing more than the cheerful, old-fashioned Sweet William. Digitalis replaces foxglove, Helianthus now dignifies the sunflower, while Ranunculus assumes responsibility for the simple little buttercup. Hundreds of other plants maintain their popularity under Latin names, and our magazines, keeping pace with the times, do not hesitate to use them. There is hope, then, that the clouds too, with us so constantly, may soon be known by their Latin names to all persons developing an appreciation of them, for the Latin simplifies classification.

Latin names and a classification of the clouds were given us by an Englishman, Luke Howard, in 1803. The present system is essentially that drawn up by the International Meteorological Committee in 1905, based upon Howard's work. The recommendations of the committee were revised in 1910 and have since been slightly modified. The names of the major cloud types with their abbreviations follow :

Cirrus Ci.

Cirro-stratus Ci.-St.

Cirro-cumulus Ci.,-Cu.

Alto-cumulus A.-Cu.

Alto-stratus A.-St.

Cumulus Cu.

Cumulo-nimbus Cu.-Nb.

Strato-cumulus St.-Cu.

Nimbus Nb.

Stratus St.

Fracto-cumulus Fr.-Cu.

Fracto-nimbus Fr.-Nb.

Fracto-stratus Fr.-St.

The altitudes of these clouds range from five to ten miles for the cirrus, the highest of all clouds, down to a half mile or mille for the nimbus and stratus. However, any one of the cloud forms can originate at low levels, although normally only the nimbus and stratus forms occur at low elevations. We have already described one of these clouds in general terms, the cumulo-nimbus. A few of the others may be pictured in the official language of the British Meteorological Office, and the story they tell of their association with the weather may be related unofficially. The formal definitions may become a bit tiring, but those who are patient with them should find themselves eventually rewarded. A little attention given the clouds each day or as incidental opportunity permits will soon bring them within our circle of friends. We may become so intimate with them that in the event our duties some days should confine us rigidly to the indoors, we shall regret having temporarily to miss association with them.

Cirrus clouds are "detached clouds of delicate appearance, fibrous (threadlike) structure, and featherlike form, generally white in color." These clouds consist of minute ice-crystals at heights of five to ten miles, which permit a considerable amount of light to pass through them. They are among the most graceful of our clouds, their thin wisps often thrown across the heavens in streamers which fray out at the ends to form the traditional mares' tails. These clouds occur at the end of a fair-weather spell and are the forerunners frequently of storminess. When in combination with cirro-stratus and cirro-cumulus clouds they are almost certain indicators of an approaching stormy period.

Cirrus clouds travel at tremendous speed, from slightly less than 100 miles an hour to approximately 250 miles. The minuteness of their particles, formed at temperatures ranging from 25° to 100° below zero Fahrenheit, offers essentially no resistance to the wind, and hence they are carried along in the westerly drift at practically the same velocity as that of the wind itself. Accordingly, by measuring the speed of the clouds we can tell the wind velocity at the cloud altitudes.

The cirro-stratus cloud is described as "a thin sheet of whitish cloud, sometimes covering the sky completely and merely giving it a milky appearance; it is then called cirro-nebula or cirrus haze ; at other times presenting, more or less distinctly, a fibrous structure like a tangled web." This type of cloud, like the cirrus made of ice-crystals, favors halos around the sun or moon. Again, as a partner of the cirrus clouds, it makes an appearance before stormy weather. The conclusion, therefore, that the "ring around the moon" is an indicator of unsettled weather has good logic in it. Naturally, the prospective precipitation is not scheduled to issue from this cloud but from others at lower altitude which follow later as a part of the general storm system.

Cirro-cumulus, the "mackerel sky small rounded masses or white flakes without shadow, or showing very slight shadow; arranged in groups and often in lines." This cloud is perhaps one of the easiest, if not the easiest, to identify because of its similarity to the design on the back of a mackerel. It is said by some that the comparison originally referred to the pattern upon a mackerel's back and not to the scales. True as this may be, we should make no mistake if we selected the cloud arrangement which resembles fish scales as cirro-cumulus clouds. Once more we have a cloud whose indications of the weather for the immediate future may not be particularly happy, for when associated with the cirrus (mares' tails) and cirro-stratus, storms are in the offing. However, should the cirro-cumulus cloud sail over us independently of these other types, it can be safely interpreted as a fair-weather bearer.

Alto-cumulus clouds are "larger rounded masses, white or grayish, partially shaded, arranged in groups or lines, and often so crowded together in the middle regions that the cloudlets join." These clouds at times resemble the cirro-cumulus, but their much larger size and lower altitude, two to three miles high, distinguish them readily. These clouds, too, when accompanying cirrus clouds, forewarn us of impending storminess.

Alto-stratus clouds, as the latter half of the name may suggest, often produce an overcast sky. They consist of "a dense sheet of a gray or bluish color, sometimes forming a compact mass of dull gray color and fibrous structure." Through this sheet of droplets of water, in contrast with the cirro-stratus sheet of ice-crystals, the light of the sun or moon passes as refracted rays, that is, rays which are bent. This bending results in the breaking up of the light into its component parts, the rainbow colors, and producing a ring of faint colors. Such a ring is a corona. The corona usually is smaller than a halo, and the red band of color in it is on the out-side of the ring, whereas in the halo, when colored, the red band, usually not so distinct, is on the inside.

The cumulus cloud, easily identified by its brilliant white boiling or billowy top, is noted appropriately as "woolpack or cauliflower cloud thick cloud of which the upper surface is dome-shaped and exhibits protuberances while the base is generally horizontal." This cloud might be named a fair-weather cloud as long as its base does not become 'too dark. When the latter effect exhibits itself and the upper parts incline some-what toward a coppery color, then the cumulus is being rapidly converted into a thunder-head, that is, the cumulo-nimbus cloud we described early in this chapter. The billowy type is more common in hot summer than in cold winter regions. It forms toward noon, reaches its climax in late afternoon, and generally evaporates by sunset.

The cumulo-nimbus cloud has already been described in general terms. Here we shall merely cite the official definition. "The thunder-cloud shower-cloud. Great masses of cloud, rising in the form of mountains or towers or animals, generally having a veil or screen of fibrous texture (false cirrus) at the top and at its base a cloud mass similar to nimbus."

Strato-cumulus clouds occur in "large lumpy masses or rolls of dull gray cloud, frequently covering the whole sky, especially in winter." Although these clouds often appear threatening, they are generally fair-weather products. They are most common in the cool autumn, the winter, and very early spring seasons. We might borrow a term from the days of the World War and describe them as "mopping-up" clouds. Usually after a rain-storm or wet snow-storm, evaporation from the earth's surface is active, and the rising water vapor condensing in the cold levels forms these dark gray more or less. parallel rows or even layerlike clouds at moderate height, perhaps a mile or a little less. While the strato-cumulus clouds usually produce a dull day, often accompanied by a chill in the air, we may feel confident that no worse weather is likely in the immediate future.

Nimbus clouds consist of "a dense layer of dark, shapeless cloud with ragged edges from which steady rain or snow usually falls. If there are no openings in the cloud, an upper layer of cirro-stratus or alto-stratus may almost invariably be seen through them." One may easily identify these clouds, for the name applies only to those in which precipitation occurs, except that when rain falls from a cumulus form this cloud, as previously explained, assumes the name cumulo-nimbus. Meteorologists and weather observers generally are not in agreement upon the definition for a nimbus cloud. Some argue that if a cloud is called nimbus when precipitation be-gins, it must have been a nimbus just before. This, however, should not be disturbing, since we have a name which may readily be applied. It is stratus, the tenth of the types in the series being discussed here.

Stratus clouds are defined as "a uniform layer of cloudlike fog not lying on the ground." Note that it is not defined as a precipitation cloud, and since its altitude may be the same as that of nimbus clouds and its form generally identical, the use of this name for potential rain or snow clouds that cover the heavens rather uniformly is practical. We have no desire here to attempt to establish a new nomenclature for clouds. In fact, we see no objection even to the naming of any cloud, not of the nimbus form, according to its particular form whenever precipitation occurs from it, as happens occasionally from the various cumulus forms. In any event, until the experts decide to agree upon the use of the term nimbus, we who are interested in the meaning of the clouds may be assured stratus at present implies that rain or snow or some other form of precipitation is possible but by no means certain. The local barometric pressure, relative humidity, and wind direction may have to be called into conference to help us determine just what the clouds are likely to do.

A glance at the table of clouds will show three types which we have not discussed. They are the "fracto" clouds. They hardly need definition, for the modifier itself implies that these clouds are similar to the pure forms but are broken or fractured. These slight modifications usually happen when the winds are fairly strong at the time of cloud formation or when convection or other currents occurring locally present further interference in the natural process of cloud-building.

The list in our table does not include all of the cloud forms. Numerous special varieties might be discussed, but owing to their somewhat restricted distribution and less frequent occurrence, we shall do no more than name a few and make a brief statement about them. The velo cloud is a type of fog which rolls in from the ocean and subsequently evaporates as the warmer air over the land establishes convection activity within it. Billowy clouds refers to clouds which assume a billowy or wavelike arrangement due to striking temperature differences in the air-layers. The lenticular cloud, known in many parts of the world by other names—"tablecloth" in South Africa, Wetterbawm (weather-tree) in the vicinity of Schneekoppe peak in the Riesen mountains between Germany and Czechoslovakia, and la serpe, the snake, in Italy —is usually an elongate cloud more or less stationary in position and associated with mountain peaks. The "mammato" clouds, a name usually descriptive of cumulus clouds, take on the appearance of a "choppy" lake and accompany squally or thunder-storm weather. The awesome "tornado" cloud we leave for the detailed discussion of tornadoes, only noting at this point that it is a funnel-shaped cloud hanging from the normal cloud mass and sometimes reaching the earth's surface. It is frequently likened to an elephant's trunk not only because of its shape but because it swings from side to side and lengthens or shortens as it leaves its trail of destruction over the country-side. Probably no display of the heaven's violence is more to be feared than this cloud which signals the approach of nature's most destructive storm.

Another cloud associated with rain-storms and particularly thunder-storms is the scud cloud. It appears as a long roll at very low altitude, usually less than 1,500 feet, just at the front of an approaching storm and below the general cloud level. The scud cloud ranges in color from a dark gray to a light smoky gray. Generally it precedes a calm, but immediately after it passes overhead we find ourselves rushing about to close windows and doors to keep out the sudden downpour of rain and the strong wind. The high wind is of short duration, since it is confined to the front of the storm, where the cool moist air of the storm proper causes an upset of the surface air as it in turn becomes cooled.

We have now run the gamut of major cloud forms as defined and described by the British Meteorological Service. Each cloud represents a combination of atmospheric conditions all of whose details we have not cited because of their complexity and the technical problems which they involve. However, enough has been said to enable any person to recognize most clouds and to appreciate what the clouds mean in relation to the current weather. The accompanying photographs should prove of additional assistance in cloud identification.

Nearly every one has enthused at the sight of an indescribable sunset behind the clouds. Artists have attempted to paint the glory of cloud colors, but the best they can ever hope for in their representation is merely to approach the richness of tones and the smooth blendings of variegated light which only nature seems competent to produce perfectly. Furthermore, the painter is handicapped when he spreads colors upon his canvas, for when he finishes, the colors remain fixed, while in nature as we observe the heavens at evening or at daybreak the color scheme is ever-changing, one color merging into another with delicate transition and delightful harmony.

When we sprinkle a lawn with a fine spray is-suing from the hose nozzle and hold the spray so as to allow the sun's rays to shine through it at certain angles, we soon discover that in some positions we can see an arc of color similar to the rainbow. The sunlight has been bent (refracted) and divided into its seven colors namely, violet, indigo (faintly) , blue, green, yellow, orange (faintly), and red, arranged in this succession. This order can be remembered from the word "vibgyor" made up of the initial letter of each word. When the sun shines upon the clouds a similar phenomenon appears as its light passes through the water vapor particles making up the cloud. However, a rainbow does not always result, but rather masses of variegated colors or shades of color emanate from the clouds and change as the angle changes at which the sun's rays strike the clouds. In the first chapter we referred to the fact that the dust of the atmosphere scatters the light. Both the dust contained within the water vapor cloud particles and free dust share in this process, and as a result of scattering, reflection from the water surfaces, and the weakening of some light rays, colors reach our eyes in unequal values and we look with admiration and sometimes reverence at the beauty of a colored sunset to which clouds have contributed.

From the succession of cloud descriptions one might gain the impression that each type of cloud dominates the heavens at a given time. While this may happen and while only one cloud type may at times be seen, quite as often more than one kind of cloud is visible at a time. The suggestion that cirrus clouds foretell unsettled weather is based upon a cloud sequence normally associated with storminess, the succession in appearance of the clouds being due largely to differences in the rates of travel. The cirrus, moving fastest, would naturally appear first, with clouds at lower altitudes following closely. Since the series of clouds usually bears a definite relation-ship to a definite combination of atmospheric pressure, temperature, moisture, and winds, we can imagine the major cloud types to be members of a sort of storm family. So it may happen that we can see four or five different clouds all at different elevations at the same time. The combinations of cloud types are of decidedly greater help in weather-forecasting than a single cloud type.

Many a community has built its prosperity upon spring waters whose chemical content has been urged upon the public as a cure for an obstreperous stomach or a lazy liver ; other centers have enticed the public to tarry awhile each year and rejuvenate itself by bathing in its hot springs ; certain cities have sounded the praises of their pure air to attract those who are unfortunate enough to have to earn a living where the air is smoke polluted; and again, many a mountain town has brought unto itself untold riches from all the world by selling its vistas from its hotel or boarding-house windows. Few, however, have featured the feast of color and inspiration offered by the clouds to those who may pass through their portals. Occasionally a folder prints a view of the setting sun, and now and then a few enthusiastic comments are offered relative to the presence of a few clouds which add to the sun's beauty; but rare indeed is the resort that takes advantage of a most valuable asset, its kaleidoscopic clouds in all their moods. To be sure, not all cities or regions have an abundance of clouds, nor are all endowed with cloud variety, but to those who have the good fortune to live where the clouds array themselves in all their possible magnificence, an opportunity awaits them which may justifiably be capitalized.