Isolated clouds often soften and beautify the stern heights as they silently float and drift among peaks and passes. Flocks of these sky birds frequently float about together. On sunny days, in addition to giving a charm to the peaks, their restless shadows never tire of readjusting themselves and are ever trying to find a foundation or a place of rest upon the tempestuous topography of the heights below. Now and then a deep, dense cloud-stratum will cover the crests and envelop the summit slopes for days. These vapory strata usually feel but little wind and they vary in thickness from a few hundred to a few thousand feet. Sometimes one of these rests so serenely that it suggests an aggregation of clouds pushed off to one side because temporarily the sky does not need them elsewhere for either decorative or precipitative purposes. Now and then they do drop rain or snow, but most of the time they appear to be in a procrastinating mood and unable to decide whether to precipitate or to move on.
Commonly the upper surfaces of cloud-strata appear like a peaceful silver-gray sea. They appear woolly and sometimes fluffy, level, and often so vast that they sweep away beyond the horizon. Peaks and ridges often pierce their interminable surface with romantic continents and islands; along their romantic shores, above the surface of the picturesque sea, the airship could sail in safe poetic flight, though the foggy depths below were too dense for any traveler to penetrate.
One spring the snow fell continuously around my cabin for three days. Reports told that the storm was general over the Rocky Mountain region. Later investigations showed that that cloud and storm were spread over a quarter of a million square miles. Over this entire area there was made a comparatively even deposit of thirty inches of snow.
All over the area, the bottom, or under surface, of the cloud was at an altitude of approximately nine thousand feet. My cabin, with an altitude of nine thousand, was immersed in cloud, though at times it was one hundred feet or so below it. Fully satisfied of the widespread and general nature of the storm, and convinced of the comparatively level line of the bottom surface of the cloud, I determined to measure its vertical depth and observe its slow movements by climbing above its silver lining. This was the third day of the storm. On snowshoes up the mountainside I went through this almost opaque sheep's-wool cloud. It was not bitterly cold, but cloud and snow combined were blinding, and only a ravine and instinct enabled me to make my way.
At an altitude of about twelve thousand feet the depth of the snow became suddenly less, soon falling to only an inch or so. Within a few rods of where it began to grow shallow I burst through the upper surface of the cloud. Around me and above there was not a flake of snow. Over the entire storm-area of a quarter of a million square miles, all heights above twelve thousand had escaped both cloud and snow. The cloud, which thus lay between the altitudes of nine thousand and twelve thousand feet, was three thousand feet deep.
When I rose above the surface of this sea the sun was shining upon it. It was a smooth sea; not a breath of wind ruffled it. The top of Long's Peak rose bald and broken above. Climbing to the top of a commanding ridge, I long watched this beautiful expanse of cloud and could scarcely realize that it was steadily flinging multitudes of snowflakes upon slopes and snows below. Though practically stationary, this cloud expanse had some slight movements. These were somewhat akin to those of a huge raft that is becalmed in a quiet harbor. Slowly, easily, and almost imperceptibly the entire mass slid forward along the mountains; it moved but a short distance, paused for some minutes, then slowly slid back a trifle farther than it had advanced. After a brief stop the entire mass, as though anchored in the centre, started to swing in an easy, deliberate rotation; after a few degrees of movement it paused, hesitated, then swung with slow, heavy movement back. In addition to these shifting horizontal motions there was a short vertical one. The entire mass slowly sank and settled two or three hundred feet, then, with scarcely a pause, rose easily to the level from which it sank. Only once did it rise above this level.
During all seasons of the year there are oft-recurring periods when the mountains sit in sunshine and all the winds are still. In days of this kind the transcontinental passengers in glass-bottomed airships would have a bird's-eye view of sublime scenes. The purple forests, the embowered, peaceful parks, the drifted snows, the streams that fold and shine through the forests,—all these combine and cover magnificently the billowed and broken distances, while ever floating up from below are the soft, ebbing, and intermittent songs from white water that leaps in glory.
Though the summits of the Rocky Mountains are always cool, it is only in rare, brief times that they fall within the frigid spell of Farthest North and become cruelly cold. The climate among these mountain-tops is much milder than people far away imagine.
The electrical effects that enliven and sometimes illuminate these summits are peculiar and often highly interesting. Thunderbolts—lightning-strokes—are rare, far less frequent than in most lowland districts. However, when lightning does strike the heights, it appears to have many times the force that is displayed in lowland strokes. My conclusions concerning the infrequency of thunderbolts on these sky-piercing peaks are drawn chiefly from my own experience. I have stood through storms upon more than a score of Rocky Mountain summits that were upward of fourteen thousand feet above the tides. Only one of these peaks was struck; this was Long's Peak, which rises to the height of 14,256 feet above the sea.
Seventy storms I have experienced on the summit of this peak, and during these it was struck but three times to my knowledge. One of these strokes fell a thousand feet below the top; two struck the same spot on the edge of the summit. The rock struck was granite, and the effects of the strokes were similar; hundreds of pounds of shattered rock fragments were flung horizontally afar. Out of scores of experiences in rain-drenched passes I have record of but two thunderbolts. Both of these were heavy. In all these instances the thunderbolt descended at a time when the storm-cloud was a few hundred feet above the place struck.