Meteorological observations at the Royal Observatory, Greenwich, during the year 1949

(Communicated by the Astronomer Royal)

The normal programme of meteorological observations at the Royal Observatory has been continued during 1949.

The maximum temperature of the air was 89.3' F, which was reached on 27 June. The cor- responding reading of the maximum thermometer exposed on the open (Glaisher) screen was 92.0". The temperature rose to 80" or above on 29 days, 12 of these in July and 9 in August. A reading of 84.0' recorded on 16 April during a very warm Easter was the highest April reading ever recorded at Greenwich.

The minimum thermometer on the Glaisher screen was stolen less than twelve hours before this minimum occurred, so that the corresponding reading on the open stand is unknown. There were 38 days on which the temperature fell to 32' or below ; 10 of these occurred in March.

The mean temperature of the year was 52.4", which is 2.7" above the 100 years' average and the Except for March and May,

The outstanding month was September with a mean temperature Six other

The minimum temperature during the year occurred on 4 February and was 19.8".

highest on record. This was the seventh consecutive warm year. every month was above average. of 63.7", 6 4 " above average, and only 0.1" cooler than the record September of 1865. months had mean readings exceeding their average by at least 3.0".

The maximum reading of the solar radiation thermometer was 1500" on 14 JuIy. The minimum temperature on the ground was 6.5" on 3 and 4 February. The difference between the highest and lowest readings of the radiation thermometers exceeded 100" on 14 days, and was greatest (1 12.5') on 2 July.

to 30.668 in. on 30 January. The reading of the barometer at 152 ft above mean sea level ranged from 28.310 in. on 1 January

The total of bright sunshine registered in the year was 1597.8 hours, which is 164 hours above This was the sunniest year since 1929 and only March, May and September were

February was the second sunniest on record with a total of 102 hours. The sunniest There were 55 entirely

the average. below average. day was 3 July with 15.2 hours, representing 92 per cent of the total possible. sunless days, only 5 of which occurred during the six months April to September.

The night sky camera recorded the trace of 6 Ursae Minoris for 46 per cent of the total exposure. Ten days were overcast throughout

The greatest daily movement was 710 miles on 4 April. The greatest hourly movement was 41 miles on 9 February, and the greatest pressure of the wind, 33.0 lb/ft*, on the same day.

The total rainfall for the year was 18.648 in. which is 5-682 in. less than the 100 years' average. Only 9.923 in. had been recorded by the end of September, whereas 5.021 in. fell in October, the only month with more than average rainfall. The largest amount on one day was 1.274 in. on 26 October. There were seven periods of ten or more consecutive days and a total of 240days on which no measurable rain fell ; the longest period being one of 19 days, 15 June to 3 July.

In comparison, 36 per cent of the possible sunshine was recorded. and three cloudless throughout.

The total horizontal movement of the air during the year was 89,517 miles.

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