Monday, January 14, 2013

It was REALLY hot in Sydney recently -- about the same as 1790 (i.e. over 200 years ago)

The following was written by Watkin Tench, a British military officer, just two years after white settlement in Australia.  Temperatures reached at least 108 F (42 degrees Celsius), similar to some records of maximum temperatures in Sydney in recent days.

The current average daily maxima for Sydney are 25.1 degrees for December and 25.8 for January.  So 1790 was a year of extreme warming desite no power stations, SUVs or factories.  There were not even many people

To convey an idea of the climate in summer, I shall transcribe from my meteorological journal, accounts of two particular days which were the hottest we ever suffered under at Sydney.

December 27th 1790. Wind NNW; it felt like the blast of a heated oven, and in proportion as it increased the heat was found to be more intense, the sky hazy, the sun gleaming through at intervals.

At 9 a.m. 85 degrees At noon; 104 Half past twelve; 107 1/2 From one p.m. until 20 minutes past two; 108 1/2 At 20 minutes past two 109 At Sunset 89 At 11 p.m. 78 1/2

[By a large Thermometer made by Ramsden, and graduated on Fahrenheit’s scale.]

December 28th.

At 8 a.m. 86 10 a.m.; 93 11 a.m.; 101 At noon; 103 1/2 Half an hour past noon; 104 1/2 At one p.m. 102 At 5 p.m. 73 At sunset 69 1/2

[At a quarter past one, it stood at only 89 degrees, having, from a sudden shift of wind, fallen 13 degrees in 15 minutes.]

My observations on this extreme heat, succeeded by so rapid a change, were that of all animals, man seemed to bear it best. Our dogs, pigs and fowls, lay panting in the shade, or were rushing into the water. I remarked that a hen belonging to me, which had sat for a fortnight, frequently quitted her eggs, and shewed great uneasiness, but never remained from them many minutes at one absence; taught by instinct that the wonderful power in the animal body of generating cold in air heated beyond a certain degree, was best calculated for the production of her young. The gardens suffered considerably. All the plants which had not taken deep root were withered by the power of the sun. No lasting ill effects, however, arose to the human constitution. A temporary sickness at the stomach, accompanied with lassitude and headache, attacked many, but they were removed generally in twenty-four hours by an emetic, followed by an anodyne. During the time it lasted, we invariably found that the house was cooler than the open air, and that in proportion as the wind was excluded, was comfort augmented.

But even this heat was judged to be far exceeded in the latter end of the following February, when the north-west wind again set in, and blew with great violence for three days. At Sydney, it fell short by one degree of what I have just recorded: but at Rose Hill, it was allowed, by every person, to surpass all that they had before felt, either there or in any other part of the world. Unluckily they had no thermometer to ascertain its precise height. It must, however, have been intense, from the effects it produced. An immense flight of bats driven before the wind, covered all the trees around the settlement, whence they every moment dropped dead or in a dying state, unable longer to endure the burning state of the atmosphere. Nor did the ‘perroquettes’, though tropical birds, bear it better. The ground was strewn with them in the same condition as the bats.

Were I asked the cause of this intolerable heat, I should not hesitate to pronounce that it was occasioned by the wind blowing over immense deserts, which, I doubt not, exist in a north-west direction from Port Jackson, and not from fires kindled by the natives. This remark I feel necessary, as there were methods used by some persons in the colony, both for estimating the degree of heat and for ascertaining the cause of its production, which I deem equally unfair and unphilosophical. The thermometer, whence my observations were constantly made, was hung in the open air in a southern aspect, never reached by the rays of the sun, at the distance of several feet above the ground.


Posted by John J. Ray (M.A.; Ph.D.).

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