Himalayan Journals Part 50

AUGUST

No. of Observations 15 26 28 28 24 23 21 21 21 Hour 1 a.m. 8 9 10 11 Noon 1 p.m. 2 3 Barom.

corrected 22.909 .904 .915 +.917 .915 .905 .898 .884 .873 Temp. Air 59.8 62.1 63.1 64.3 64.7 64.7 65.3 65.0 64.8 D.P. 59.5 61.5 61.9 62.7 63.1 63.4 63.3 63.4 63.1 Diff. 0.3 0.6 1.2 1.6 1.6 1.3 2.0 1.6 1.7 Tens. of Vapour .514 .549 .558 .572 .580 .586 .584 .586 .579 Weight of Vapour 5.70 6.13 6.20 6.35 6.42 6.50 6.48 6.50 6.43 Humidity .992 .980 .962 .950 .948 .958 .940 .950 .943 Press. of Dry Air +22.395 .355 .357 .345 .335 .319 .314 .298 .294

No. of Observations 19 19 19 19 19 19 19 19 19 Hour 4 p.m. 5 6 7 8 9 10 11 M.n.

Barom.

corrected 22.855-.853 .863 .865 .878 .890 +.823 .892 .889 Temp. Air 63.9 63.2 62.3 61.6 61.1 60.7 60.3 60.1 60.0 D.P. 62.4 61.7 60.8 60.4 60.2 60.0 59.7 59.7 59.4 Diff. 1.5 1.5 1.5 1.2 0.9 0.7 0.6 0.4 0.6 Tens. of Vapour .568 .554 .538 .531 .527 .523 .518 .517 .513 Weight of Vapour 6.30 6.15 6.00 5.92 5.88 5.85 5.78 5.79 5.73 Humidity .952 .952 .952 .952 .970 .976 .980 .988 .980 Press. of Dry Air -.287 .299 .325 .334 .351 .367 .375 .375 .376

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 pa.s.sage 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 cla.s.sing 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

DORJILING No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 15 The Dale* 6956 ft. 9.50 a.m. 42.9 32.4 10.5 .202 15 Mr. Muller's ... Noon 45.8 33.8 12.0 .212 10 ... ... 2.40 p.m. 48.3 37.4 10.9 .241 8 ... ... 4 p.m. 48.6 37.8 10.8 .244 9 ... ... Sunset 46.5 37.1 9.4 .238 --------------------------------------------------------------------- 57 ... ... Mean 46.4 35.7 10.7 .227 ---------------------------------------------------------------------

CALCUTTA No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 15 The Dale* 6956 ft. 9.50 a.m. 67.5 55.3 12.2 .446 15 Mr. Muller's ... Noon 72.9 55.7 17.2 .455 10 ... ... 2.40 p.m. 76.1 55.1 21.0 .444 8 ... ... 4 p.m. 75.1 54.8 20.3 .440 9 ... ... Sunset 71.8 54.9 16.9 .441 --------------------------------------------------------------------- 57 ... ... Mean 72.7 55.2 17.5 .445 ---------------------------------------------------------------------

*Observations to which the asterisk is affixed were taken by Mr. Muller.

Dorjiling.--Humidity 0.700 Calcutta 0.562 ,, Vapour in cubic foot of atmosphere 2.63 gr. ,, 4.86 gr.

JANUARY, 1850 DORJILING No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 3 Jillapahar, 7430 ft. Sunrise 32.8 30.1 2.7 .186 6 Mr. Hodgson's ... 9.50 a.m. 39.5 34.7 4.8 .219 3 ... ... Noon 42.4 38.0 4.4 .246 5 ... ... 2.40 p.m. 41.9 37.8 4.1 .244 5 ... ... 4 p.m. 41.1 38.5 2.6 .250 5 ... ... Sunset 38.7 35.6 3.1 .226 13 ... ... Miscel. 41.9 39.9 2.0 .263 4 Saddle of road 7412 ft. Do. 41.1 36.4 4.7 .233 at Sinchul.

1 Pacheem. 7258 ft. Do. 39.8 38.7 1.1 .252 --------------------------------------------------------------------- 45 ... ... Mean 39.9 36.6 3.3 .235 ---------------------------------------------------------------------

CALCUTTA No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 3 Jillapahar, 7430 ft. Sunrise 51.5 48.5 3.0 .354 6 Mr. Hodgson's ... 9.50 a.m. 66.9 55.1 11.8 .444 3 ... ... Noon 74.1 51.7 22.4 .395 5 ... ... 2.40 p.m. 78.3 51.4 26.9 .391 5 ... ... 4 p.m. 77.4 59.5 17.9 .514 5 ... ... Sunset 72.4 54.7 17.7 .438 13 ... ... Miscel. 77.9 60.1 17.8 .525 4 Saddle of road 7412 ft. Do. 67.7 57.2 10.5 .476 at Sinchul.

1 Pacheem. 7258 ft. Do. 71.6 50.5 21.2 .379 --------------------------------------------------------------------- 45 ... ... Mean 70.9 54.3 16.6 .435 ---------------------------------------------------------------------

Dorjiling.--Humidity 0.890 Calcutta 0.580 ,, Weight of vapour 2.75 gr. ,, 4.86 gr.

FEBRUARY DORJILING No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 3 Jillapahar, 7430 ft. Sunrise 36.9 34.7 2.2 .219 18 1850 ... 9.50 a.m. 42.9 38.6 4.3 .251 12 ... ... Noon 44.8 41.3 3.5 .276 12 ... ... 2.40 p.m. 44.8 37.4 7.4 .241 17 ... ... 4 p.m. 44.0 35.6 8.4 .226 19 ... ... Sunset 42.4 35.8 6.6 .228 13 The Dale* 6956 ft. Miscel. 40.8 35.1 5.7 .222 --------------------------------------------------------------------- 97 ... ... Mean 42.4 36.9 5.4 .238 ---------------------------------------------------------------------

CALCUTTA No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 3 Jillapahar, 7430 ft. Sunrise 60.0 54.2 5.8 .431 18 1850 ... 9.50 a.m. 72.8 58.8 14.0 .503 12 ... ... Noon 79.8 58.7 21.2 .501 12 ... ... 2.40 p.m. 82.4 57.9 24.5 .487 17 ... ... 4 p.m. 81.1 58.1 23.0 .492 19 ... ... Sunset 76.3 60.7 15.6 .536 13 The Dale* 6956 ft. Miscel. 69.9 59.8 10.1 .518 --------------------------------------------------------------------- 97 ... ... Mean 74.6 58.3 16.3 .495 ---------------------------------------------------------------------

Dorjiling.--Humidity 0.828 Calcutta 0.590 ,, Weight of vapour 2.75 gr. ,, 5.40 gr.

MARCH DORJILING No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 10 Jillapahar, 7430 ft. 9.50 a.m. 44.2 42.7 1.5 .290 8 1850 ... Noon 45.5 43.0 2.5 .293 5 ... ... 2.40 p.m. 46.4 44.0 2.4 .303 8 ... ... 4 p.m. 45.5 43.4 2.1 .297 6 ... ... Sunset 43.1 41.5 1.6 .278 3 Pacheem. 7258 ft. Misc. 44.8 44.6 0.2 .310 --------------------------------------------------------------------- 40 ... ... Mean 44.9 43.2 1.7 .295 ---------------------------------------------------------------------

CALCUTTA No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 10 Jillapahar, 7430 ft. 9.50 a.m. 81.6 64.1 17.5 .602 8 1850 ... Noon 88.2 57.0 31.2 .472 5 ... ... 2.40 p.m. 91.3 53.2 38.1 .416 8 ... ... 4 p.m. 90.1 52.0 38.1 .399 6 ... ... Sunset 82.9 63.7 19.2 .590 3 Pacheem. 7258 ft. Misc. 85.0 74.8 10.2 .848 --------------------------------------------------------------------- 40 ... ... Mean 86.5 60.8 25.7 .555 ---------------------------------------------------------------------

Dorjiling.--Humidity 0.940 Calcutta 0.438 ,, Weight of vapour 3.42 gr. ,, 5.72 gr.

APRIL DORJILING No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 3 Jillapahar, 7430 ft. 9.50 a.m. 57.0 40.2 16.8 .266 3 1849 ... Noon 59.8 44.1 15.7 .305 1 ... ... 2.40 p.m. 60.2 44.4 15.8 .308 7 Dr. Campbell's 6932 ft. 9.50 a.m. 61.8 53.3 8.5 .417 2 1850 ... Noon 65.4 52.8 12.6 .411 4 ... ... 4 p.m. 57.5 53.7 13.8 .423 3 ... ... Sunset 56.9 51.4 5.5 .392 --------------------------------------------------------------------- 23 ... ... Mean 59.8 48.6 11.3 .360 ---------------------------------------------------------------------

CALCUTTA No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 3 Jillapahar, 7430 ft. 9.50 a.m. 90.3 71.3 19.0 .758 3 1849 ... Noon 97.0 64.5 32.5 .607 1 ... ... 2.40 p.m. 97.7 73.4 24.3 .812 7 Dr. Campbell's 6932 ft. 9.50 a.m. 86.7 66.3 20.4 .644 2 1850 ... Noon 91.3 68.8 22.5 .699 4 ... ... 4 p.m. 88.6 72.1 16.5 .778 3 ... ... Sunset 82.8 73.0 9.8 .800 --------------------------------------------------------------------- 23 ... ... Mean 90.6 69.9 20.7 .728 ---------------------------------------------------------------------

Dorjiling.--Humidity 0.684 Calcutta 0.523 ,, Weight of vapour 3.98 gr. ,, 7.65 gr.

MAY DORJILING No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 3 Smith's Hotel, 6863 ft. Misc. 57.2 55.0 2.2 .443 1848 45 Colinton,* 7179 ft. Misc. 60.4 57.9 12.5 .466 1849 --------------------------------------------------------------------- 48 ... ... Mean 58.8 56.5 12.4 .455 ---------------------------------------------------------------------

CALCUTTA No. of Obs. Place Elev. Hour Tp. D.P. Diff. Tens.

--------------------------------------------------------------------- 3 Smith's Hotel, 6863 ft. Misc. 88.6 78.4 10.2 .951 1848 45 Colinton,* 7179 ft. Misc. 90.0 77.2 12.8 .917 1849 --------------------------------------------------------------------- 48 ... ... Mean 89.3 77.8 11.5 .934 ---------------------------------------------------------------------

Dorjiling.--Humidity 0.926 Calcutta 0.698 ,, Weight of vapour 5.22 gr. ,, 9.90 gr.