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Centre for Atmospheric Science

An Early Report on Urban Meteorology

Comparison of Observations of Temperature taken at two stations in Manchester from December 4th, 1892, to January 28th, 1893. By J. Wilson. Communicated by Arthur Schuster, Ph.D., F.R.S., F.R.A.S.

Published in Memoirs and Proceedings of The Manchester Literary and Philosophical Society, Series 4, Vol 7, pp 160-168, 1893.

Since August, 1892 systematic meteorological observations have been taken at the Observatory in Whitworth Park, Manchester. These have been compared with similar readings taken at the Oldham Road (the "Manchester City") Observatory, and it has been thought that a short summary of the results of such a comparison would not be without interest to members of this Society.

The period chosen for a detailed comparison extends from December 4th, 1892, to January 28th 1893; this being selected as it contains the periods of lowest temperature of the winter 1892-3.

The Oldham Road Observatory is situated in an industrial area on the north side of the town, Whitworth Park being in a residential area on the south side. Both stations are about one mile distant from the centre of the city.

All the observations are taken at 9 a.m. The thermometers at both observatories have been verified at Kew, and they are exposed in Stevenson's screens, 4 ft. high, over grass.

The observations which have been tabulated are the following:
I. Maxima in the shade.
II. Minima in the shade.
III. Means of I. and II.
IV. Temp, at 9 a m. in the shade.

The following Tables explain themselves; the period to which the numbers apply is the 24 hours ending at 9 a.m. on the date given in the first column. The differences for the maxima have been formed by subtracting the Oldham Road from the Whitworth Park observations, while in the case of the minima the observations taken at the latter place are subtracted from those taken at the former.

(1) December 4th to 10th

W.P. = Whitworth Park; O.R. = Oldham Road.

Max Min Mean Temp. at 9 a.m.
24 hours ending 9 a.m. on W.P. O.R. Diff. W.P. O.R. Diff. W.P. O.R. W.P. O.R.
Sun Dec 4 45.7 44 1.7 30 30.2 0.2 37.9 37.1 30.2 31
Mon Dec 5 35.3 33.4 1.9 17.2 25.2 8 26.3 29.3 21.4 26.3
Tue Dec 6 33.4 35 -1.6 19.8 25.8 6 26.6 30.4 33.4 34.8
Wed Dec 7 39.8 39.8 0 29.4 30.3 0.9 34.6 35.1 36.7 35.2
Thur Dec 8 40.2 38.8 1.4 22.5 26.6 4.1 31.4 32.7 27.3 30.5
Fri Dec 9 37.2 36.6 0.6 27.1 30 2.9 32.2 33.3 36.3 36
Sat Dec 10 37.8 36.4 1.4 20.7 25.4 4.7 29.3 30.9 23.4 27.2
Sums 269.4 264 5.4 166.7 193.5 26.8 218.3 228.9 208.7 221
Mean 38.5 37.7 0.8 23.8 27.6 3.8 31.2 32.7 29.8 31.6

 

(2) December 11th to 17th

Max Min Mean Temp. at 9 a.m.
24 hours ending 9 a.m. on W.P. O.R. Diff. W.P. O.R. Diff. W.P. O.R. W.P. O.R.
Sun Dec 11 39.4 40.1 -0.7 20.3 26.8 6.5 29.9 33.5 36.3 38.2
Mon Dec 12 43.8 43.8 0 35.6 38.4 2.8 39.7 41.1 40.8 41.8
Tue Dec 13 45.2 42.6 2.6 31.4 35.4 4 38.3 39 35.6 35.4
Wed Dec 14 43.9 43.5 0.4 31 35.2 4.2 37.5 39.4 43.9 43.5
Thur Dec 15 50.8 50.8 0 41.7 43.3 1.6 46.2 47.1 44.6 45.9
Fri Dec 16 52.6 51.9 0.7 33.3 38.8 5.5 42.9 45.4 36.1 40.5
Sat Dec 17 49.8 49.4 0.4 35.5 40.3 4.8 42.7 44.7 49.1 49.4
Sums 325.5 322.1 3.4 228.8 258.2 29.4 277.2 290.2 286.4 294.7
Mean 46.5 46 0.5 32.7 36.9 4.2 39.6 41.5 40.9 42.1

 

(3) December 18th to 24th

Max Min Mean Temp. at 9 a.m.
24 hours ending 9 a.m. on W.P. O.R. Diff. W.P. O.R. Diff. W.P. O.R. W.P. O.R.
Sun Dec 18 52.5 52.3 0.2 44.8 46.8 2 48.7 49.6 50.5 50
Mon Dec 19 57.7 52.9 4.8 47.2 48.5 1.3 52.5 50.7 47.7 48.3
Tue Dec 20 51.9 49 2.9 40.4 43.2 2.8 46.2 46.1 41.5 43.2
Wed Dec 21 48.4 46.3 2.1 41 43.2 2.2 44.7 44.8 43.7 45.3
Thur Dec 22 49.1 46 3.1 35 37.7 2.7 42.1 41.9 37.4 38.5
Fri Dec 23 47.3 44.2 3.1 32.1 34.5 2.4 39.7 39.4 36.5 37.4
Sat Dec 24 39.4 38.9 0.5 28.4 30.3 1.9 33.9 34.6 29.1 30.8
Sums 346.3 329.6 16.7 268.9 284.2 15.3 307.8 307.1 286.4 293.5
Mean 49.5 47.1 2.4 38.4 40.6 2.2 44 43.9 40.9 41.9

 

(4) December 25th to 31st

Max Min Mean Temp. at 9 a.m.
24 hours ending 9 a.m. on W.P. O.R. Diff. W.P. O.R. Diff. W.P. O.R. W.P. O.R.
Sun Dec 25 33.6 33.9 -0.3 27.3 27.2 -0.1 30.5 30.6 30.8 29
Mon Dec 26 37.3 34.8 2.5 17.1 21 3.9 27.2 27.9 18.1 22.2
Tue Dec 27 32.6 27.6 5 14.7 20 5.3 23.7 23.8 16.2 20.9
Wed Dec 28 28.9 26.4 2.5 15.3 20.4 5.1 22.1 23.4 16.5 21
Thur Dec 29 31.5 30 15 16.2 21 4.8 23.9 25.5 24.3 24.8
Fri Dec 30 36.2 35.8 0.4 23.6 24.6 1 29.9 30.2 26.6 29.1
Sat Dec 31 35.8 35.3 0.5 22.7 27.1 4.4 29.3 31.2 34.9 35.2
Sums 235.9 223.8 12.1 136.9 161.3 24.4 186.6 192.6 167.4 182.2
Mean 33.7 32 1.7 19.6 23 3.4 26.7 27.5 23.9 26

 

(5) January 1st to 7th

Max Min Mean Temp. at 9 a.m.
24 hours ending 9 a.m. on W.P. O.R. Diff. W.P. O.R. Diff. W.P. O.R. W.P. O.R.
Sun Jan 1 36.8 35.3 1.5 24.9 26.8 1.9 30.9 31.1 26.2 27.1
Mon Jan 2 32.9 31.7 1.2 22 22 0 27.5 26.9 23 23
Tue Jan 3 33.4 33.4 0 17.8 22.2 4.4 25.6 27.8 33.4 33.4
Wed Jan 4 35.1 34.3 0.8 12.4 21 8.6 23.8 27.7 13.1 21
Thur Jan 5 20 28.8 -8.8 8.8 19.7 10.9 14.4 24.3 16.7 27.4
Fri Jan 6 32.3 33 -0.7 16.2 27.5 11.3 24.3 30.3 30.2 32.1
Sat Jan 7 32.8 32.7 0.1 29 30 1 30.9 31.4 31.5 31.6
Sums 223.3 229.2 -5.9 131.1 169.2 38.1 177.4 199.5 174.1 195.6
Mean 31.9 32.7 -0.8 18.7 24.2 5.5 25.3 28.5 24.9 27.9

 

(6) January 8th to 14th

Max Min Mean Temp. at 9 a.m.
24 hours ending 9 a.m. on W.P. O.R. Diff. W.P. O.R. Diff. W.P. O.R. W.P. O.R.
Sun Jan 8 35.8 35 0.8 31.1 28.8 -2.3 33.5 31.9 35.1 35
Mon Jan 9 37.8 37.2 0.6 34.4 34.3 -0.1 36.1 25.8 37 36.5
Tue Jan 10 38.7 38 0.7 35.2 35.3 0.1 36.9 36.7 38.5 38
Wed Jan 11 40.7 39 1.7 31.6 32.4 0.8 36.2 35.7 37 36.6
Thur Jan 12 39.9 38.8 1.1 34.6 34.7 0.1 37.3 36.8 36.1 37.5
Fri Jan 13 40.8 39.5 1.3 35 35.6 0.6 37.9 37.6 36.9 36.4
Sat Jan 14 41.8 41.1 0.7 32.6 33.8 1.2 37.2 37.4 35.4 35.1
Sums 275.5 268.6 6.9 234.5 234.9 0.4 255.1 251.9 356 255.1
Mean 39.4 38.4 1 33.5 33.6 0.1 36.4 36 36.6 36.4

 

(7) January 15th to 21st

Max Min Mean Temp. at 9 a.m.
24 hours ending 9 a.m. on W.P. O.R. Diff. W.P. O.R. Diff. W.P. O.R. W.P. O.R.
Sun Jan 16 37 36.2 0.8 25.5 27.8 2.3 31.3 32 26.4 28
Mon Jan 16 34.2 34.9 -0.7 26.1 28 1.9 30.2 31.5 34.2 34.9
Tue Jan 17 42 41 1 33.5 34.3 0.8 37.8 37.7 35.1 35.8
Wed Jan 18 43.5 44 -0.5 32.6 34.1 1.5 38.1 39.1 43.2 44
Thur Jan 19 48 46 2 37.1 41.1 4 42.6 43.6 37.6 42.2
Fri Jan 20 46.2 45.2 1 36 38.1 2.1 41.1 41.7 36.7 38.5
Sat Jan 21 45.7 43 2.7 35.6 37.2 1.6 40.7 40.1 40.1 39.4
Sums 296.6 290.3 6.3 226.4 240.6 14.2 261.8 265.7 253.3 262.8
Mean 42.4 41.5 0.9 32.3 34.4 2.1 37.4 38 36.2 37.5

 

(8) January 22nd to 28th

Max Min Mean Temp. at 9 a.m.
24 hours ending 9 a.m. on W.P. O.R. Diff. W.P. O.R. Diff. W.P. O.R. W.P. O.R.
Sun Jan 22 44.8 43 1.8 39.8 39.3 -0.5 42.3 41.2 43.2 43
Mon Jan 23 50.3 46 4.3 42.9 42.6 -0.3 46.6 44.3 45.5 45.4
Tue Jan 24 49 47.8 1.2 44.2 45 0.8 46.6 46.4 45 45.5
Wed Jan 25 52 49.2 2.8 35.5 40.4 4.9 43.8 44.8 37.4 41.8
Thur Jan 26 49.5 47.1 2.4 37.4 40.3 2.9 43.5 43.7 42.6 45
Fri Jan 27 47.8 25.2 2.6 28.9 34.1 5.2 38.4 39.7 32 35.5
Sat Jan 28 49 44.9 4.1 31.7 35.6 3.9 40.4 40.3 37.9 38.4
Sums 342.4 323.2 19.2 260.4 277.3 16.9 301.6 300.4 283.6 294.6
Mean 48.9 46.2 2.7 37.2 39.6 2.4 43.1 42.9 40.5 42.1

 

Summary of Weekly Means.

Max Min Mean Temp. at 9 a.m.
W.P. O.R. Diff. W.P. O.R. Diff. W.P. O.R. W.P. O.R.
Dec 4-10 38.5 37.7 0.8 23.8 27.6 3.8 31.2 32.7 29.8 31.6
Dec 11-17 46.5 46 0.5 32.7 36.9 4.2 39.6 41.5 40.9 42.1
Dec 18-24 49.5 47.1 2.4 38.4 40.6 2.2 44 43.9 40.9 41.9
Dec 25-31 33.7 32 1.7 19.6 23 3.4 26.7 27.5 23.9 26
Jan 1-7 31.9 32.7 -0.8 18.7 24.2 5.5 25.3 28.5 24.9 27.9
Jan 8-14 39.4 38.4 1 33.5 33.6 0.1 36.4 36 36.6 36.4
Jan 15-21 42.4 41.5 0.9 32.3 34.4 2.1 37.4 38 36.2 37.5
Jan 22-28 48.9 46.2 2.7 37.2 39.6 2.4 43.1 42.9 40.5 42.1
Sums 330.8 321.6 9.2 236.2 259.9 23.7 283.7 291 273.7 285.5
Mean 41.1 40.2 1.2 29.5 32.5 3 35.5 36.4 34.2 35.7

 

I. Maxima.

Generally speaking, the maxima at Whitworth Park are higher than the corresponding readings at Oldham Road, the daily average for the period in question at the former observatory being 4i.4°F, and at the latter 40.2°F. In this connection it may be noted that during the month of January 17hrs, 20min of bright sunshine were registered at Whitworth Park, as compared with l0hrs, 45mins during the corresponding period at Oldham Road, although it must be pointed out that for January there does not appear to be any connection between the differences in the maxima and the differences in the amount of bright sunshine on a given day. The greatest divergence 8.8°F between the maxima occurs on Jan. 5th.

Percentage of Maxima greater at Whitworth Park than at Oldham Road.
Percentage of higher readings observed 82%
Percentage of equal readings observed 7%
Percentage of higher readings calculated 86%

The calculated percentage is obtained by assuming that in half the cases in which the readings were equal, the temperature was really higher in the Park maximum than in the Oldham Road maximum.

 

II. Minima.

The minima show a much greater difference than do the maxima, the daily average being 29.5°F and 32.5°F at Whitworth Park and Oldham Road respectively. The days marked by the greatest divergences are December 5, December 6, January 4, January 5, and January 6, these being also the days of greatest cold.

Date Difference between Minima.   Minimum Reading at Whitworth Park.  
Dec. 5 8.0 17.2
Dec. 6 6.0 19.8
Jan. 4 8.6 12.4
Jan. 5 10.9 8.8
Jan. 6 11.3 16.2

The coldest week at Oldham Road was Dec. 25 - 31, the daily average for the minima being 23.0°F, whereas the coldest week at Whitworth Park was the following week, the daily average being 18.7°F.

Percentage of Minima Readings lower at Whitworth Park than at Oldham Road.
Percentage of lower readings observed 89%
Percentage of equal readings observed 2%
Percentage of lower readings calculated 90%

 

III. Means.

68 per cent, of the means are higher at Oldham Road than at Whitworth Park, the daily averages being 36.4°F and 35.5°F respectively.

 

IV. 9 a.m. Readings.

Generally speaking, the readings at Whitworth Park are lower than at Oldham Road, the daily averages being 34.2°F and 35.7°F respectively.

Percentage of lower readings observed 88%
Percentage of equal readings observed 2%
Percentage of lower readings calculated 89%

 

Mean Daily Range.

The mean daily range is less at Oldham Road than at Whitworth Park, the values being respectively 7.7°F and 11.9°F. Taking the series of readings as a whole the greatest divergence occurs on January 5th, the figures for the day being:

  Maximum in shade. Minimum. Mean. 9 a.m. Readings.
Whitworth Park 20.0   8.8   14.4   16.7  
Oldham Road 28.8 19.7 24.3 27.4
Difference 8.8 10.9 9.9 10.7

 

Note on the previous paper. By Arthur Schuster, Ph.D., F.R.S., F.R A.S.

Mr. Wilson, a few weeks ago, drew my attention to a curious difference in the record of the minimum temperature as observed in the City Observatory, Oldham Road, and the Owens College Observatory, Whitworth Park. I asked him to write a short account of his observations, because it seemed to me that, although the time over which the observations extend is short, the results were definite, and suggested several matters to which our attention will have to be directed in future.

The remarkable differences which appear in the temperature records in different parts of the city furnish an additional proof, if proof were wanted, that observations taken in or near a large town cannot be taken to represent correctly the meteorological character of the surrounding districts, but it by no means follows that these observations are of no value. On the contrary, they may lead to some important conclusions on what may be called town weather as distinguished from country weather.

It seems to me that the differences in the minimum temperatures are accounted for by the fact that the smoke hanging over the city prevents a free radiation into space at night. The smaller the amount of dust and smoke the lower would be the minimum temperature. The effect of smoke is so considerable that the differences between the Oldham Road and Whitworth Park observations amount, as Mr. Wilson has shown, in some cases to 11 degrees, and it would be interesting to have some records still nearer the centre of the city.

The lessening of cold in winter nights might not seem at first sight to be an object for regret, but it must be remembered that the same cause which shelters the town against the effects of radiation, will prevent the sunlight from having its due effect in daytime. Consequently, in the month of January, Oldham Road only registered 62% of the sunlight registered at Whitworth Park; and here it must again be remembered that the Oldham Road Observatory is not near the centre of the city, nor is the Whitworth Park very far removed from it. How much greater, then, may we expect to find the differences existing between the centre of the town and the country.

The effect of smoke seems so considerable, and its effects appear so rapidly, that there is a marked difference in the behaviour of the Oldham Road Observatory on Sundays and other days. I was struck by the fact that on only 5 occasions did the Oldham Road Observatory record lower temperatures than the Whitworth Park, and all five cases happened during the night from Saturday to Sunday, or from Sunday to Monday. I have arranged Mr. Wilson's record according to the days of the week, and the result is shown in the following table.

Night from. Difference in the mean record of minimum temperature at Oldham Road and Whitworth Park.
Saturday to Sunday 1.25
Sunday to Monday 2.l6
Monday to Tuesday 3.13
Tuesday to Wednesday 3.53
Wednesday to Thursday 3.91
Thursday to Friday 3.86
Friday to Saturday 2.94

 

No very certain conclusions can be drawn from the record of a few weeks only, but it is certainly suggestive that while the mean difference on Saturday and Sunday nights is 1.7°F only, the mean difference during the rest of the week is double that number, or 3.4°F.

In future observations attention will be directed to these differences as depending on the general state of the atmosphere. In conclusion, I should like to state that I shall be glad to receive the names of gentlemen residing in different parts of Manchester who would volunteer to take regular records, especially of sunshine, the instruments being supplied to them.