336 CORRESPONDENCE AND NOTES Royal Observatory, Greenwich. Report to the Council of the Royal Meteorological Society for the year 19U. (Communicated by the Astronomer Royal.) Meteorological observations have been continued as last year. In addition, regular observations of " visibility " according to the Inter- national scale were commenced as from October 1st. The Observatory also took part in the International photographic cloud survey in the last week of September. The temperature of the air varied between 9zO.z F. on July 11, and 2z0.7F. on November 26. It reached 80' on 25 days, two of which were in the first week of May (a phenomenon only once previously recorded-in 1867)~ fourteen in July and nine in August. On four days-three in July and one in August-the maximum temperature exceeded goo. Air temperatures of 32O or less were recorded on 39 days, the largest number included in one month being fourteen in December, while November followed closely with twelve. The mean temperature for the year was 49O.7, being oO.1 above the average. Of the sepamte months, the first three were about 3' above the average; June was 4" below, November 4O.7 below, and July 3O.9 above the average. 1,376 hours of bright sunshine were recorded. The first six months were all deficient, June particularly so, only one-fifth of the possible amount occurring in that month. December also was remarkably dull, having only sixteen hours sunshine. Of these, thirteen were in December, and ten each in January and February. Three days had at least go per cent. of possible sunshine, the sunniest day being July 9, with 14.2 hours, though August 22, with 13.4 hours, had actually a greater percentage of possible sunshine. The highest reading of the solar radiation thermometer with black bulb in vucuo was 165O.o on July 8, and the lowest reading on the grass was I+O.O on November 12. The difference between the highest and lowest radiation readings exceeded 10oO on 37 days, the greatest difference being 126O.4 on August 5. The total rainfall was 23.95 inches, or 0.38 inches below the average 1841-1920. The outstanding months were June with 0.48 inches, and October with 3.03 inches. The longest period without rain lasted from August z to 14. 1.88 inches fell in the two days July g and 10, and both October 3 and 12 were credited with a fall of more than three- quarters of an inch. There were 171 "raindays " in the year, 23 of which were in October and 21 in February. The total movement of the air recorded by Robinson's anemometer was 10j,812 miles. The greatest pressure recorded was 17.8 Ibs. on the square foot on April 26. The greatest daily movement was 650 miles on August 30. and the greatest hourly velocity was 44 miles, for the hour ending midnight on November 15. The least daily movement was qa miles on November 26. There were 67 sunless days.

Royal Observatory, Greenwich. Report to the council of the Royal Meteorological Society for the year 1923

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Page 1: Royal Observatory, Greenwich. Report to the council of the Royal Meteorological Society for the year 1923

336 CORRESPONDENCE AND NOTES

Royal Observatory, Greenwich. Report to the Council of the Royal Meteorological Society for the year 19U. (Communicated by the Astronomer Royal.)

Meteorological observations have been continued as last year. In addition, regular observations of " visibility " according to the Inter- national scale were commenced as from October 1st. The Observatory also took part in the International photographic cloud survey in the last week of September. The temperature of the air varied between 9zO.z F. on July 1 1 , and 2z0.7F. on November 26. I t reached 80' on 25 days, two of which were in the first week of May (a phenomenon only once previously recorded-in 1867)~ fourteen in July and nine in August. On four days-three in July and one in August-the maximum temperature exceeded goo. Air temperatures of 32O or less were recorded on 39 days, the largest number included in one month being fourteen in December, while November followed closely with twelve.

The mean temperature for the year was 49O.7, being o O . 1 above the average. Of the sepamte months, the first three were about 3' above the average; June was 4" below, November 4O.7 below, and July 3O.9 above the average.

1,376 hours of bright sunshine were recorded. The first six months were all deficient, June particularly so, only one-fifth of the possible amount occurring in that month. December also was remarkably dull, having only sixteen hours sunshine. Of these, thirteen were in December, and ten each in January and February. Three days had a t least go per cent. of possible sunshine, the sunniest day being July 9, with 14.2 hours, though August 22, with 13.4 hours, had actually a greater percentage of possible sunshine.

The highest reading of the solar radiation thermometer with black bulb in vucuo was 165O.o on July 8, and the lowest reading on the grass was I+O.O on November 12. The difference between the highest and lowest radiation readings exceeded 10oO on 37 days, the greatest difference being 126O.4 on August 5 .

The total rainfall was 23.95 inches, or 0.38 inches below the average 1841-1920. The outstanding months were June with 0.48 inches, and October with 3.03 inches. The longest period without rain lasted from August z to 14. 1.88 inches fell in the two days July g and 10, and both October 3 and 12 were credited with a fall of more than three- quarters of an inch. There were 171 "ra indays " in the year, 23 of which were in October and 21 in February.

The total movement of the air recorded by Robinson's anemometer was 10j,812 miles. The greatest pressure recorded was 17.8 Ibs. on the square foot on April 26. T h e greatest daily movement was 650 miles on August 30. and the greatest hourly velocity was 44 miles, f o r the hour ending midnight on November 15. The least daily movement was qa miles on November 26.

There were 67 sunless days.