Читать книгу The Romance of Modern Geology. Describing in simple but exact language the making of the earth with some account of prehistoric animal life онлайн

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Such are the cyclones which are in the main part responsible for British weather; and the winds that accompany them vary a great deal in strength. They depend on the size of the eddy. If the eddy is a very big one (and sometimes the eddies are thousands of miles across) the winds will not be so strong as in the smaller ones. It is, therefore, the smaller ones which cause the violent storms. In the tropical regions whirling eddies of a rather different character occur. To quote Mr. J. H. N. Stephenson: "Instead of being measured by some hundreds or even thousands of miles, they are usually only some hundreds of yards across; and as we found that the smaller the cyclone the more violent the wind, we shall not be surprised that the wind in these is more violent than anything we ever experience in this part of the world. They are called by many different names; in the West Indies they are known as hurricanes, in the south-east of Asia as typhoons, and in North America as tornadoes. These hurricanes or tornadoes travel much faster than the larger cyclones, and the winds blowing into them are so violent that everything—trees, houses, bridges—are swept before them, and so strong is the in-draught of air in the centre that strong walls are sucked in just as a piece of paper is in front of a grate when the fire begins to blaze up; and even heavy metal objects are carried upwards. Fortunately these tornadoes do not travel continuously along the ground but bump along it, so to speak, sometimes passing harmlessly overhead, then striking the earth again and causing more havoc. Where they pass over the surface of the sea the water is sometimes sucked in just in the same way, causing what is known as a waterspout. These may do even more damage than a tornado on land, for the water is sometimes carried bodily on to the land, sweeping everything away in a deluge. This happened many years ago in the delta of the Ganges, when thousands of people perished."