Tornado - one of the most destructive and frightening weather phenomena, the huge rotating air column falling from clouds to the earth. These whirlwinds can be noticeable from far away and to be almost invisible, to arise in desert steppes and to come to the land from the ocean.
It is required to you
- Automobile first-aid kit, a set of first aid, the computer with the connected Internet.
Instruction
1. The facts of emergence of a tornado becomes known regularly, during the whole year on all continents – in Australia and Europe, Africa and Asia. Nevertheless, still remains a zone of the most frequent tornadoes to the USA where them there are more than one thousand annually. After contact with the earth's surface, the way of a tornado usually makes not less than several kilometers though the facts of the large-scale destructions caused by a tornado on routes up to 50 kilometers long were recorded. At the same time width of such way was more than 1 kilometer. Wind speed in a tornado reaches 160 km/h, but in the most severe cases can exceed and 400km/h.
2. To classify a tornado, it is necessary to know that the same as hurricanes and tropical storm, a tornado have various forms and the sizes. They can differ from weak (most widespread) to extremely strong and cruel which diameter of a column reaches 2 kilometers. According to the tornadoes given long-term meteorological observations, more than sixty percent – weak. Such cause no more than five percent of death, they stick to no more than 1 - 10 minutes, and wind speed in them approximately 180-320km/h. Strong tornadoes are registered in twenty nine percent of cases. Such whirlwinds bear more than thirty percent of death and not less than twenty minutes are observed. Cruel tornadoes – the most terrible category. Such there are no more than two percent. But they bring not less than seventy percent of fatal cases and last not less than an hour.
3. Now there are practically no ways which would allow to measure wind speed in a tornado. As the destructive force of an air column surpasses strength of measuring designs and materials. Therefore the existing gradation of intensity of a tornado is based on assessment of the destructions made by it. Such measuring system carries the name of the Expanded Scale of Fudzhito (EF) by the name of professors of the University of Chicago of the USA of Ted Fudzhito. Fudzhito for the first time developed the system in 1971. Originally it was called a F-scale. On it classification of a tornado from F0 – the weakest, to F5 – the strongest was carried out. Speed of wind was determined by force of influence of an air column and help data on what force is necessary for destruction of different standard constructions. Later, at the beginning of the 90th, the changes connected in progress in the field of construction and technologies and understanding of what influence forces for destruction of trees, automobiles, high-rise buildings have to be were entered into this system.