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15
METEOROLOGICAL OBSERVATIONS.
I am indebted to Sir H. Spencer Jones, F.R.S., Astronomer
Royal, for the following meteorological data for the year ended
December, 1946.
The mean temperature was 50.0°, which is 0.3° higher than the
average for the 100 years 1841-1940. The highest temperature in the
shade was 87.0° on July 24th. Temperatures exceeding 80.0° were
recorded on nine days. The lowest temperature was 19.0° on
December 21st. Temperatures of freezing point, or below, were
recorded on sixteen days in both January and December, and on
nineteen other days, a total of 51 days. During November, the
temperature did not fall below 34.0°, which was a record for that
month.
The mean daily horizontal movement of the air was 269 miles,
which is sixteen miles below the average for 50 years, 1867-1916.
The greatest daily movement was 737 miles on February 8th ; the
least daily movement was 77 miles on March 24th. The greatest
motion in one hour was 40 miles on February 23rd and September
20th, and the greatest pressure was 31.0 lbs. to the square foot on
August 28th.
The duration of bright sunshine recorded was 1,331.6 hours or
30 per cent, of the possible total. The sunniest day was July 10th
with 13.6 hours.
There were 79 entirely sunless days, of which eight were in the
period of six months April to September.
The total rainfall was 27.72 inches, which is 3.39 inches more
than the average for the 100 years 1841-1940. October was the
driest month with 0.71 inch ; August was the wettest month with
4.23 inches. Measurable rain fell on 187 days. The five months
May to September had a record total of 90 rainy days, which is
48 per cent, above average. July 26th was the wettest day with
1.45 inches. There was no period of absolute drought. The longest
periods without rain were January 13th to 25th and March 23rd to
April 4th, both of 13 days.
With regard to pollution of the air by solids in suspension, a
bad period was December 10th to 14th. At one time during
December 12th, the amount reached 4.2 milligrams per cubic metre,
that is approximately 7 lbs. in the volume of air contained in a cub
with one hundred yards edge.