frame five question and answers on cyclone and floods.
Answers
Answer:
This is Your Answer
Explanation:
Please Follow Me
Answer:
1. What is a tropical cyclone?
A tropical cyclone (TC) is a rotational low-pressure system in tropics when the
central pressure falls by 5 to 6 hPa from the surrounding and maximum sustained
wind speed reaches 34 knots (about 62 kmph). It is a vast violent whirl of 150 to 800
km, spiraling around a centre and progressing along the surface of the sea at a rate
of 300 to 500 km a day.
The word cyclone has been derived from Greek word ‘cyclos’ which means
‘coiling of a snake’. The word cyclone was coined by Heary Piddington who worked
as a Rapporteur in Kolkata during British rule. The terms "hurricane" and "typhoon"
are region specific names for a strong "tropical cyclone". Tropical cyclones are called
“Hurricanes” over the Atlantic Ocean and “Typhoons” over the Pacific Ocean.
2. Why do ‘tropical cyclones' winds rotate counter-clockwise (clockwise) in the
Northern (Southern) Hemisphere?
The reason is that the earth's rotation sets up an apparent force (called the
Coriolis force) that pulls the winds to the right in the Northern Hemisphere (and to the
left in the Southern Hemisphere). So, when a low pressure starts to form over north
of the equator, the surface winds will flow inward trying to fill in the low and will be
deflected to the right and a counter-clockwise rotation will be initiated. The opposite
(a deflection to the left and a clockwise rotation) will occur south of the equator.
This Coriolis force is too tiny to effect rotation in, for example, water that is
going down the drains of sinks and toilets. The rotation in those will be determined
by the geometry of the container and the original motion of the water. Thus, one can
find both clockwise and counter-clockwise flowing drains no matter what hemisphere
you are located. If you don't believe this, test it out for yourself.
3. What is the energy potential of a Tropical Cyclone?
Tropical Cyclone can be compared to a heat engine. The energy input is from
warm water and humid air over tropical oceans. Release of heat is through
condensation of water vapour to water droplets/rain. Only a small percentage (3%) of
this released energy is converted into Kinetic energy to maintain cyclone circulation
(windfield). A mature cyclone releases energy equivalent to that of 100 hydrogen
bombs.
4. How are low pressure system classified in India? What are the differences
between low, depression and cyclone?
The low-pressure systems over Indian region are classified based on the
maximum sustained winds speed associated with the system and the pressure
deficit/ number of closed isobars associated with the system. The pressure criteria is
used when the system is over land and wind criteria is used, when the system is
over the sea. The system is called as low if there is one closed isobar in the interval
of 2 hPa. It is called depression, if there are two closed isobars, a deep depression, if
there are three closed isobars and cyclonic storm if there are four or more closed
isobars. The detailed classification based on wind criteria are given in the Table
below. Considering wind criteria, the system with wind speed of 17-27 knots is called
as depression and the low pressure system with maximum sustained 3 minutes
surface winds between 28-33 knots is called a deep depression. The system with
maximum sustained 3 minutes surface winds of 34 knots or more is called as
cyclonic storm.
5. Are all cyclonic storms equally dangerous?
No, all cyclonic storms are not equally dangerous. More the pressure drop at
the central region more will be the severity of the storm. The cyclonic storms are
generally categorised according to the maximum wind associated with the storm. If
the maximum wind is between 34 - 47 knots (about 62-88 kmph) it is called a
Cyclonic storm. Severe Cyclonic storm will have maximum wind speed between 48 -
63 knots (about 89-117 kmph). If the maximum wind is 64-89 knots it will be called a
very severe Cyclonic storm. If the maximum wind is 90-119 knots it will be called as
Extremely Severe Cyclonic storm and when the wind is 120 knots and above it will
be called super cyclonic storm. There is very little association between intensity
(either measured by maximum sustained winds or by the lowest central pressure)
and size (measured by radius of gale force winds)
6. What is the intensity of a cyclone?
Intensity of a cyclone can be derived as the near-surface maximum wind
speed around the circulation centre, or as the minimum surface pressure at the
tropical cyclone pressure centre. The intensity classification of cyclone as per their
intensity given in the table above.