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The solution of the tasks arisen here depends on data that have different origin. The
scale allows a tornado
'
s wind speed to be determined by various means:
visiting the tornado damage site to make non-engineering assessments;
obtaining an engineering assessment of the damage;
using Doppler radar;
applying photogrammetric analysis; and
directly measuring observed tornadoes.
Whose solution permits us to forecast the hurricane origin and prognosis of its
category.
7.3 Tropical Cyclone as Dynamic Category
of the Environmental Phenomena
Tropical cyclone refers to the category of natural disasters the origin and evolution
of which does not depend on the human. Walker (2003) and Grigoriev and
Kondratyev (2001) noted that number of natural catastrophes increased during last
time. For example, up to 1990 during all of foregoing 30 years more thousand
tornadoes was registered in USA only in 1973 but this level is exceeded during last
time regularly.
Unstable atmospheric systems (tornadoes and hurricanes) have large destructive
power but they differ on origin, frequency and spatial scales. Only on the USA
territory, 10
1,200 tornadoes are beginning during a year.
Ahurricane can cover a space up to 2,000 km whereas a tornado has a moving band
no more than 4 km (Figs.
7.1
and
7.2
). Some statistics given in Figs.
7.3
,
7.4
and
Table
7.5
shows how the number of natural catastrophes changes and the conse-
quences arisen from them.
Thereby, many authors associate the natural catastrophenatural notion with the
notion of ecological security. This is arisen in connection with the necessity of
danger assessment for population of some territory that can lose health, buildings or
property because of the environment change. These changes can be caused by
natural or anthropogenic reasons. In the
15 hurricanes and 1,000
-
-
uc-
tuations of natural processes connected with synoptic changes, epidemic occur-
rence, or natural hazard. In the second case, risk originates from a nature reaction on
human actions. For example, Gardner (2002) analyzed environmental changes in
the Himalayas on Indian territory and came to the conclusion that such facts as
deforestation and vegetation cover change were stimulus and intensi
first case, dangerous origins due to
fl
ers of insta-
bilities in this region. This is characterized by degradation of soil resources and
increase of consequences from
oods.
Historic knowledge about consequences of tropical cyclones practically is absent.
It is obstacle to determine a correlation between tropical cyclones and other natural
processes. There exists fragmentary information about separate episodes of tropical
fl
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