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Notes and Comments
blossomed during June this year almost immediately after it was planted in a coconut-shell. (In the Herbarium it is represented by Metcalf 18,005). This is a very characteristic species and is easily recognized by the distichous leaves and dainty white flowers which come out on what appear almost to be dead stems.
Eria coronaria Reichb. is represented by the live number 2757, collected on Shap-Man-Tai-Shan in November 1934 by Tsang, Wai-Tak. These plants were planted in flower pots and blossomed on February 20th, 1935. (In the Herbarium it is represented by Metcalf 17,973). numerous yellow and reddish brown flowers are very attractive.
FRANKLIN P. METCALF,
Curator of Herbarium.
The
METEOROLOGY. January-June, 1935. January on the whole was dull and humid; there were nine completely sunless days, and the total sunshine for the month was 39 hours less than normal. Although the month was abnormally cloudy, there was very little rainfall. February opened with a spell of wet weather, rain or drizzle falling every day until the 11th; on the 12th the weather cleared up, and no rain was recorded during the remainder of the month. The 12th to the 17th were days of almost unbroken sunshine. March came in and went out with cloudy damp spells, while ten days in the middle of the month were warm and sunny.
The first half of April was cloudy, wet, and often foggy. Towards the end of the month the weather improved, and continued mainly fair until the middle of May; we were lucky to have a sunny spell for the Jubilee celebrations, more than to hours of sunshine being recorded on each day from the 6th to the 9th. In the latter half of May and the whole of June the weather was normal for the time of year-mainly cloudy and showery, with with occasional sunny days. Up to the end of June the total rainfall for the year was still 10 inches short of the normal; every month except March had been deficient in rain.
At the time of writing (July) we are in the midst of the rainy season; sometimes in a tropical downpour it seems little short of miraculous that such deluges of water can be produced out of empty air, and some notes on the formation of rain may be of interest at this time of year.
As any school geography book tells us, rain is caused by the raising and consequent cooling of damp air; but the books are necessarily a little vague when they come to deal with the actual physical processes which go on inside a rain-cloud, for these are difficult to observe and are not yet fully understood.
Air can contain a limited quantity of invisible water-vapour; when this limit is reached, the air is said to be saturated, and its relative humidity is then 100%. The amount of water-vapour needed to saturate a sample of air increases with the temperature of the latter. Consequently if damp air is cooled, a temperature will eventually be reached at which it becomes saturated with water-vapour; any further cooling must result in some of the water-vapour condensing in the form of visible droplets, which we see as a mist or cloud.
The Hong Kong Naturalist.