Page:Mongolia, the Tangut country, and the solitudes of northern Tibet vol 2 (1876).djvu/293

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EXTREME HEAT AND TORNADOES.
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appear above the horizon than it scorched us mercilessly. In the daytime the heat enveloped us on all sides, above from the sun, below from the burning ground; the wind, instead of cooling the atmosphere, stirred the lower strata and made it even more intolerable. On these days the cloudless sky was of a dirty hue, the soil heated to 145° Fahr., and even higher where the sands were entirely bare, whilst at a depth of two feet from the surface it was 79°.

Our tent was no protection, for it was hotter within than without, although the sides were raised. We tried pouring water on it, and on the ground inside, but this was useless, in half an hour everything was as dry as before, and we knew not whither to turn for relief.

The air, too, was terribly dry;[1] no dew fell, and rain-clouds dispersed without sending more than a few drops to earth. We observed this interesting phenomenon several times, particularly in Southern Ala-shan near the Kan-su mountains, where the rain, as it fell, met the lower heated atmosphere and passed off in steam[2] before reaching the earth. Thunderstorms rarely occurred,[3] but the wind was incessant night and day, and sometimes blew with great violence, chiefly from the south-east and south-west. On calm days tornadoes were frequent about the middle of the day or a little later. To avoid the

  1. The difference between the wet and dry bulbs of the thermometer was sometimes as great as 39°, with the temperature at 113°.
  2. This phenomenon only occurred when the clouds were too small to cool the atmosphere sufficiently.
  3. Only three times in July.