F 3
Thermometers.-All thermometers in use are compared with Kew Standard No. 647 in winter and summer.
III.-METEOROLOGICAL OBSERVATIONS AT THE OBSERVATORY.
Automatic records of the temperature of the air and evaporation were obtained with a Richard dry and wet bulb thermograph, and of the direction and velocity of the wind with a Beckley and a Dines-Baxendell Anemograph, modified as described in the report for 1912. The amount of rain is recorded automatically by a Nakamura pluviograph and the amount of sunshine by two Campbell-Stokes universal sunshine recorders. Eye observations of barometric pressure, temperature of the air and of evaporation and the amount of cloud are made at each hour of Hongkong Standard time. The character and direction of the motion of the clouds are observed every three hours. Daily readings are taken of self-registering maximum and minimum thermometers.
Principal features of the Weather.-The principal features of the weather in 1925 were:-
(a) Heavy rain in June and July.
(b) Temperature considerably below normal from April 4 to 18.
Barometric pressure was considerably above normal in April, October and December. It was considerably below normal in January, and moderately below in March, May and August. The mean pressure for the year at station level was 29.845ins. as against 29.830ins in 1924 and 29.842 for the past 42 years. The highest pressure was 30.343 on December 30 as against 30.314ins in 1924 and 30.509ins for the past 42 years. The lowest pressure was 29.272ins on July 14 as against 29.365ins in 1924, and 28.590ins. for the past 42 years.
The temperature of the air was considerably below normal in April and moderately below in January and February. It was moderately above normal in November. The mean temperature for the year was 71.4 as against 72.3 in 1924 and 71.9 for the past 42 years. The highest temperature was 92.8 on August 28, as against 93.2 in 1924 and 97.0 for the past 42 years. The lowest temperature was 39.7 on February 1 as against 47.5 in 1924 and 32.0 for the past 42 years. The mean temperature for April, 65.2, was the lowest on record.
The rainfall was considerably above normal in March, June, and July and considerably below in May and August. The total for the year was 87.58 as against 98.57ins in 1924 and 85.19 for the past 42 years. The greatest fall in one civil day was 10.38ins. on July 17 as against 20.495 for the past 42 years, and the greatest in one hour was 3.16ins between 10.30 p.m. and 11.30 p.m. on June 15 as against 3.480ins for the past 42 years.