child's knowledge about Nature's wonders. Perhaps now is the time to
increase your child's knowledge about Nature's forces.
What are hurricanes?
Hurricanes are strong wind storms, which are cyclonic in nature. This
means that they revolve around a central point, which is known as an
'eye'. The eye is the calmest part in the storm, while the winds raging
around the storm have reached a speed of 119 km an hour! The winds
rotate in an anti-clockwise direction in the northern hemisphere, and
in a clockwise direction in the southern hemisphere.
How are hurricanes formed?
Hurricanes are formed in tropical, ocean areas. The warm air
above the ocean begins to rise, and as it rises, it condenses and forms
clouds and rain droplets. The process of condensation always results in
the release of heat. So when the heated air rises and releases heat
during condensation, the surrounding air also becomes warm. This warm
air rises further, and then gets blown away by the high altitude winds,
and cold air is pushed down to the ocean. The cold air then becomes
warm because of the warmth of the ocean, and rises up again and is
blown away. In addition, converging winds over the ocean (winds that
run into each other) also push the ocean air upwards. Since the ocean
air is in any case rising when they are warmed, the converging winds
make it rise even faster. Thus, due to these phenomena, the movement of
air increasingly becomes more and more rapid.
What are tornadoes?
Far more violent than hurricanes are tornadoes. Winds
surrounding tornadoes often reach speeds of 100 miles an hour, and have
even reached speeds of 300 miles an hour.
How are tornadoes formed?
Tornadoes are usually formed from thunderstorms and can be
defined as a extending from the base of a
thundercloud to the ground. To put it simply, thunderstorms that rage
in the sky 'drop' what appears to be a rope, but is actually a gust of
wind moving in a circular direction. When this 'rope' touches the
ground, it wreaks havoc.
Tornadoes are formed in a similar manner as hurricanes. Warm,
moist air rises up and condenses, releasing heat and forming a
thundercloud and rain. (Tornadoes are thus often accompanied by rain,
and can cause flooding.) This continuous rise of air upwards is called
an 'updraft', and a low pressure area is created in the center. High
pressure cold winds are then sucked inwards, and the colliding forces
causes the thunderstorm to rage.
These clouds are often green in colour, and at times the sky
too turns green - a phenomenon that scientists still don't have an
explanation for. Hurricanes and tornadoes are similar to the extent
that they both have a cyclonic movement, which means that they rotate
around an eye. A tornado's movement, as we have seen, is far swifter
and more centered.
How are tornadoes ranked?
Tornadoes are ranked on a six-tiered "Fujita Scale". A rank of
F0 means that the tornado is weak and has caused a minimal of damage,
while a rank of F6 means that the tornado was severe and has caused
many deaths and damage to property. The vortex of a tornado is a
dangerous place to be because here is where there is maximum rain and