Himalayan Journals, vol 2 by J. D. Hooker (great reads TXT) 📖
- Author: J. D. Hooker
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DECEMBER
No. of
Observations 28 29 28 24 23 23 23 23 23
Hour 8 a.m. 9 10 11 Noon 1 p.m. 2 3 4
Barom.
corrected 23.000 .013 +.018 .009 22.995 .980 .962 .947 -.944
Temp. Air 59.2 60.1 60.8 61.6 62.4 62.7 62.8 62.3 61.8
D.P. 58.1 58.5 59.5 60.0 60.5 60.5 60.4 60.0 59.9
Diff. 1.1 1.6 1.3 1.6 1.9 2.2 2.4 2.3 1.9
Tens. of
Vapour .492 .497 .514 .523 .533 .532 .531 .522 .521
Weight of
Vapour 5.50 5.57 5.77 5.83 5.93 5.92 5.90 5.83 5.82
Humidity .968 .945 .958 .950 .942 .942 .925 .924 .940
Press. of
Dry Air 22.508 .516 .504 .506 .462 .448 .431 .425 -.423
No. of
Observations 19 19 20 21 22 24 24 23
Hour 5 p.m. 6 7 8 9 10 11 M.n.
Barom.
corrected 22.944 .948 .958 .975 .986 +.991 .989 .994
Temp. Air 60.3 59.4 58.7 58.2 57.8 57.4 57.0 56.7
D.P. 58.6 58.4 57.4 57.0 56.6 56.4 55.9 55.4
Diff. 1.7 1.0 1.3 1.2 1.2 1.0 1.1 1.3
Tens. of
Vapour .498 .496 .479 .473 .467 .463 .456 .449
Weight of
Vapour 5.58 5.58 5.60 5.33 5.25 5.23 5.15 5.07
Humidity .940 .968 .960 .962 .960 .968 .962 .927
Press. of
Dry Air .446 .452 .479 .502 .519 .528 .533 +.545
OCTOBER (22 days)
No. of
Observations 11 19 20 20 19 13 15 13 13 14
Hour 6-6.30 a.m. 7 8 9 10 11 Noon 1 p.m. 2 3
Barom.
corrected 23.066 .072 .086 .099 +.100 .079 .072 .055 .033 .027
Temp. Air 54.4 54.3 55.2 56.3 57.1 57.6 57.9 58.0 57.7 57.9
D.P. 52.7 52.3 53.7 54.4 55.5 55.6 56.1 56.4 56.6 56.2
Diff. 1.7 2.0 1.5 1.9 1.6 2.0 1.8 1.6 1.1 1.7
Tens. of
Vapour .4.9 .403 .423 .434 .450 .451 .459 .463 .466 .460
Weight of
Vapour 4.65 4.58 4.78 4.90 5.07 5.08 5.15 5.17 5.25 5.16
Humidity .943 .925 .950 .935 .942 .935 .940 .950 .962 .940
Press. of
Dry Air +22.657 +.669 .663 .665 .650 .628 .613 .592 .567 .567
No. of
Observations 16 13 6 7 3 7 14 18 14
Hour 4 p.m. 5 6 7 8 9 10 11 M.n.
Barom.
corrected 23.024 -.022 .033 .045 .038 .061 +.072 .067 .068
Temp. Air 57.9 56.6 55.9 55.4 53.7 55.1 54.6 54.5 54.1
D.P. 56.1 54.8 54.4 53.8 53.3 54.1 53.0 53.0 52.8
Diff. 1.8 1.8 1.5 1.6 0.4 1.0 1.6 1.5 1.3
Tens. of
Vapour .458 .439 .433 .424 .417 .429 .413 .413 .411
Weight of
Vapour 5.15 4.98 4.90 4.80 4.75 4.83 4.82 4.82 4.65
Humidity .940 .948 .950 .950 .990 .965 .949 .950 .962
Press. of
Dry Air -.566 .583 .600 .621 .621 .632 .659 .654 .657
APPENDIX G.
ON THE RELATIVE HUMIDITY, AND ABSOLUTE AMOUNT OF VAPOUR
CONTAINED IN THE ATMOSPHERE AT DIFFERENT ELEVATIONS IN
THE SIKKIM HIMALAYA.
My observations for temperature and wet-bulb being for the most part desultory, taken at different dates, and under very different
conditions of exposure, etc., it is obvious that those at one station are hardly, if at all, comparative with those of another, and I have therefore selected only such as were taken at the same date and hour with others taken at the Calcutta Observatory, or as can easily be
reduced; which thus afford a standard (however defective in many
respects) for a comparison. I need hardly remind my reader that the vapour-charged wind of Sikkim is the southerly one, which blows over Calcutta; that in its passage northwards to Sikkim in the summer
months, it traverses the heated plains at the foot of the Himalaya, and ascending that range, it discharges the greater part of its
moisture (120 to 140 inches annually) over the outer Himalayan
ranges, at elevations of 4000 to 8000 feet. The cooling effect of the uniform covering of forest on the Sikkim ranges is particularly
favourable to this deposition, but the slope of the mountains being gradual, the ascending currents are not arrested and cooled so
suddenly as in the Khasia mountains, where the discharge is
consequently much greater. The heating of the atmosphere, too, over the dry plains at the foot of the outer range, increases farther its capacity for the retention of vapour, and also tends to render the
rain-fall less sudden and violent than on the Khasia, where the south wind blows over the cool expanse of the Jheels. It will be seen from the following observations, that in Sikkim the relative humidity of the atmosphere remains pretty constantly very high in the summer
months, and at all elevations, except in the rearward valleys; and
even there a humid atmosphere prevails up to 14,000 feet, everywhere within the influence of the snowy mountains. The uniformly high
temperature which prevails throughout the summer, even at elevations of 17,000 and 18,000 feet, is no doubt proximately due to the
evolution of heat during the condensation of these vapours. It will be seen by the pages of my journal, that continued sunshine, and the consequent heating of the soil, is almost unknown during the summer, at any elevation on the outer or southward ranges of Dorjiling: but the sunk thermometer proves that in advancing northward into the
heart of the mountains and ascending, the sun's effect is increased, the temperature of the earth becoming in summer considerably higher than that of the air. With regard to the observations themselves,
they may be depended upon as comparable with those of Calcutta, the instruments having been carefully compared, and the cases of
interpolation being few. The number of observations taken at each
station is recorded in a separate column; where only one is thus
recorded, it is not to be regarded as a single reading, but the mean, of several taken during an hour or longer period. I have rejected all solitary observations, even when accompanied by others at Calcutta; and sundry that were, for obvious reasons, likely to mislead. Where many observations were taken at one place, I have divided them into sets, corresponding to the hours at which alone the Calcutta
temperature and wet-bulb thermometer are recorded,* [Sunrise; 9.50
a.m.; noon; 2.40 p.m.; 4 p.m., and sunset.] in order that
meteorologists may apply them to the solution of other questions
relating to the distribution of heat and moisture. The Dorjiling
observations, and those in the immediate neighbourhood of that
station, appeared to me sufficiently numerous to render it worth
while classing them in months, and keeping them in a series by
themselves. The tensions of vapour are worked from the wet-bulb
readings by Apjohn's formula and tables, corrected for the height of the barometer at the time. The observations, except where otherwise noted, are taken by myself.
SERIES I. Observations made at or near Dorjiling.
JANUARY, 1849
DORJILINGNo. of
Obs. Place Elev. Hour
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