Travelling over the sea the whirlies displayed fresh capabilities. Columns of brash-ice, frozen spray and water-vapour were frequently seen lifted to heights of from two hundred to four hundred feet, simulating water spouts.
Reverting to the afternoon of March 19. Beyond the strange stillness of the immediate vicinity, broken occasionally by the tumult of a passing, wandering whirly, an incessant, seething roar could be heard. One could not be certain from whence it came, but it seemed to proceed either from the south or overhead. Away on the icy promontories to the east and west, where the slopes were visible, mounting to an altitude of several thousand feet, clouds of drift-snow blotted out the details of the surface above a level of about six hundred feet. It certainly appeared as if the gale, for some reason, had lifted and was still raging overhead. At 7.30 P.M. the sound we had heard, like the distant lashing of ocean waves, became louder. Soon gusts swept the tops of the rocky ridges, gradually descending to throw up the snow at a lower level. Then a volley raked the Hut, and within a few minutes we were once more enveloped in a sea of drifting snow, and the wind blew stronger than ever.
The duration of the lulls was ordinarily from a few minutes to several hours; that of March 19 was longer than usual. In the course of time, after repeated observations, much light was thrown on this phenomenon. On one occasion, a party ascending the ice slopes to the south met the wind blowing at an elevation of four hundred feet. At the same time snow could be seen pouring over the "Barrier" to the west of the Winter Quarters, and across a foaming turmoil of water. This was evidently the main cause of the seething roar, but it was mingled with an undernote of deeper tone from the upland plateau—like the wind in a million tree-tops.
In the early spring, while we were transporting provisions to the south, frequent journeys were made to higher elevations. It was then established that even when whole days of calm prevailed at the Hut, the wind almost without exception blew above a level of one thousand feet. On such occasions it appeared that the gale was impelled to blow straight out from the plateau slopes over a lower stratum of dead-air. An explanation was thereby afforded of the movement of condensation clouds which appeared in the zenith at these times. A formation of delicate, gauzy clouds developed at a low altitude, apparently in still air, but doubtless at the base of a hurricane stratum. Whirling round rapidly in eddying flocculi, they quickly tailed away to the north, evaporating and disappearing.
The auditory sense was strangely affected by these lulls. The contrast was so severe when the racking gusts of an abating wind suddenly gave way to intense, eerie silence, that the habitual droning of many weeks would still reverberate in the ears. At night one would involuntarily wake up if the wind died away, and be loth to sleep "for the hunger of a sound." In the open air the stillness conveyed to the brain an impression of audibility, interpreted as a vibratory murmur.
During one hour on March 22 it blew eighty-six miles. On the morning of that day there was not much snow in the air and the raging sea was a fearful sight. Even the nearest of the islands, only half a mile off the land, was partially hidden in the clouds of spray. What an impossible coast this would be for the wintering of a ship!
Everybody knows that the pressure exerted by a wind against an object in its path mounts up in much greater proportion than the velocity of the wind. Thus may be realized the stupendous force of the winds of Adelie Land in comparison with those of half the velocity which fall within one's ordinary experience. As this subject was ever before us, the following figures quoted from a work of reference will be instructive. The classification of winds, here stated, is that known as the "Beaufort scale." The corresponding velocities in each case are those measured by the "Robinson patent" anemometer; our instrument being of a similar pattern
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Beaufort scale |Velocities|Pressures | Apparent effect |
| in miles | in lbs. | |
| per hour | square | |
| foot | |
| | area | |
__________________|__________| _________|_________________________|
0|Calm | 2 | 0.02 |May cause smoke to |
| | | | move form vertical |
1|Light air | 4 | 0.06 |Moves the leaves of trees|
2|Light breeze | 7 | 0.19 |Moves small branches of |
3|Gentle breeze | 10 | 0.37 | trees and blows up dust |
4|Moderate breeze| 14 | 0.67 | |
5|Fresh breeze | 19 | 1.16 |Good sailing breeze and |
6|Strong breeze | 25 | 1.90 | makes white caps |
7|Moderate gale | 31 | 2.81 |Sways trees and breaks |
8|Fresh gale | 37 | 3.87 | small branches |
9|Strong gale | 44 | 5.27 |Dangerous for sailing |
10|Whole gale | 53 | 7.40 | vessels |
11|Storm | 64 | 10.40 |Prostrates exposed trees |
12|Hurricane | 77 | 14.40 | and frail houses |
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Beyond the limits of this scale, the pressures exerted rise very rapidly. A wind recorded as blowing at the rate of a hundred miles per hour exerts a pressure of about twenty-three pounds per square foot of surface exposed to it. Wind above eighty miles per hour is stated to "prostrate everything."
The mileages registered by our anemometer were the mean for a whole hour, neglecting individual gusts, whose velocity much exceeded the average and which were always the potent factors in destructive work.