After each fall of snow, the weather usually became bright and calm, with a serene cloudless sky. The sun shone out brightly, and was agreeably warm to the feel, while the temperature of the air rose nearly to, or a little above, the freezing-point. In the earlier part of the winter, the snow melted rapidly, and the ground in the open valley was generally nearly free of it before the next fall. After the beginning of January, however, the cold increased, and the snow lay permanently, except on the most sunny slopes. The sun seemed to have much less power, and little thaw took place except on rocks and beaten paths. The diminution in the quantity of snow by evaporation was often considerable.
The greatest cold which was registered at Iskardo was at daybreak on the 8th of February, when Fahrenheit's thermometer stood at half a degree above zero. The mean temperature at sunrise during the whole winter was 19½°, and that at two P.M. 33¾°. The mean temperature during the period from the 28th of December to the 31st of January was 27½°, and from the 1st to the 24th of February 25¾°. The increase of cold was principally by the depression of the night temperature, the mean highest temperature being within a fraction of a degree the same during both periods.
On the first or second day of clear weather after a fall of snow, the temperature in the morning was often very low, with abundant hoar-frost, which, except at such times, was not seen at all. The surface of the plain was covered with a dense fog, which remained till nearly noon before the sun was able to dispel it. On the second or third day the sky would become hazy, the sun being partly obscured by a thin stratum of cloud at a great elevation. During the continuance of this haze, the temperature was always more elevated than when the sky was clear. The hazy weather was once or twice dissipated by violent winds, without any fall of snow on the open plain; but more generally it increased gradually, till the sky was completely and densely overcast, and snow began again to fall, perhaps most frequently during the night.
During the greater part of the winter the snow was invariably in extremely minute grains. It was not till the latter part of February, when spring was rapidly approaching, that large flakes fell. I more than once observed the phenomenon of small quantities of extremely fine-grained snow falling when the sky was quite clear, and the air at the surface of the earth quite motionless. During clear weather very little thaw took place, the cold produced by radiation appearing to counteract the sun's action; at the same time the snow diminished rapidly by evaporation, which was not the case when the sky was overcast.