The roads were nearly empty but low visibility made driving treacherous.
The visibility of a star is a question of brightness simply, and has nothing to do with resolving power.
Even if it hadn't been dark, visibility would have been less than a few feet.
In the Ephemerides published year by year, the times of new moon were given, together with the calculated intervals to the first visibility of the crescent, from which the beginning of each month was reckoned; the dates and circumstances of solar and lunar eclipses were predicted; and due information was supplied as to the forthcoming heliacal risings and settings, conjunctions and oppositions of the planets.
Was it possible to make a private deal, outside the visibility of the other deities?
In the first place it increased the visibility of the signalling instrument; in the second place it brought that instrument into the position in which it could most readily catch the operator's eye; and finally it eliminated the effort involved in associating one piece of apparatus with another and in finding that other.
So in the microscope there is nothing except lack of light to hinder the visibility of an object however small.
These attain their maximum visibility when the plane of analysation is at 45° to these planes, and vanish when the plane of polarization is parallel to either of the principal planes.
- The action of moonlight necessarily gives rise to a true lunar period in the visibility of aurora.
A transparent atmosphere and clear horizon are necessary, conditions which can best be secured on a mountain top. The visibility of a light corresponding to the inference was shown by Simon Newcomb, by observations at the top of the Brienzer Rothorn, in 1905.
Disk to depths of 31 and 36 fathoms in the Sargasso Sea, but in the cold currents of the north and also in the equatorial current the depth of visibility was only from zi to 162 fathoms. to the tropical parts of the Indian and the Pacific Oceans the depth of visibility increases again to from 20 to 27 fathoms. Some allowance should be made for the elevation of the sun at the time of observation.
Mill has shown that in the North Sea off the Firth of Forth the average depth of visibility of a disk in the winter half-year was 4; fathoms and in the summer half-year 62 fathoms, and, although the greater frequency of rough weather in winter might tend to obscure the effect, individual observations made it plain that the angle of the sun was the main factor in increasing the depth to which the disk remained visible.
Even at Cape Thorsden, the sun at midwinter is only I I° below the horizon at noon, and its effect on the visibility is thus not wholly negligible.
William Gascoigne was the first who practically appreciated the chief advantages of the form of telescope suggested by Kepler, viz., the visibility of the image of a distant object simultaneously with that of a small material object placed in the common focus of the two lenses.
Having this position, the conditions of visibility will be best when the ecliptic, and therefore the axis of the light, are nearly perpendicular to the horizon, and, as the angle between the ecliptic and horizon becomes acute, will deteriorate, slowly at first, more and more rapidly afterwards, owing to the increasing effect of atmospheric absorption.
The latter possibility is also suggested by the curious fact that the visibility of the light does not seem to be proportional to the transparency of the atmosphere.
Perhaps all metals are crystalline, only the degree of visibility of the crystalline arrangement is very different in different metals, and even in the same metal varies according to the slowness of solidification and other circumstances.
Since that time nine novas have appeared, which have attained naked-eye visibility; and in recent years a number of very faint objects of the same class have been detected.
These, however, since they share the general lengthening or shortening of wave-length through motion, are thereby shifted, to a certain definite extent, into visibility, and so produce accurate chromatic compensation.
He was still above the timberline, devoid of any trees that would impair visibility so it was clear enough to follow the road with its many switchbacks and curves traversing the mountain below him, a black line clinging to the side of the cliff like a pencil drawing.
She applied the brakes and the dust cloud caught up, cloaking the road so thickly that visibility was down to the front of the car.
At several stations enjoying a wide prospect the dissipation has been observed to be specially high on days of great visibility when distant mountains can be recognized.
Reason says: (1) space with all the forms of matter that give it visibility is infinite, and cannot be imagined otherwise.