Tornado, It’s Dangers
Tornado occur when the conditions that cause thunderstorms are
unusually violent. Winds blow in opposite directions around a strong updraft
start a narrow, violent whirl. Centrifugal force effectively throws the air
away from the center, leaving a core of very low pressure. This is much like
stirring water in a cup, thus forming a vortex like dip in the surface.
This low pressure core acts as a
partial vacuum, sometimes helping to lift the roofs of houses. Most of the
damage, though, result from the force of wind itself. Around the edges or the
whirl, wind speeds may reach 300 miles (480 kilometers) per hour.
At
first, the tornado’s funnel is whitish-gray because it’s composed of minute
water droplets formed as the air in the funnel expands and cools. After
touching down, the funnel becomes dark because of all of the debris it has
picked up. This debris can include soil, tree limbs, and parts of building,
tornado have been known to pick up automobiles, horses and whole trees.
A tornado usually moves toward the
east (or often northeast in the Northern Hemisphere and Southeast Hemisphere) at 25 to 40 miles (40 to 65
kilometers) per hour. Fortunately, most tornadoes are less than half a mile
(800 meters) wide; the edge of one may destroy all of the houses on one side of
a street while leaving those on the other side completely undamaged.
Deaths from tornadoes in the United
States averages roughly 100 per year over the last century. However, they have
dropped somewhat in recent decades as better forecasting and warning system
have been implemented.
0 comments :