Contribution of butterfly to cyclone Titli

 

How in god’s name is that possible? How can something comparatively as irrelevant as a butterfly

have any impact on something as big as a cyclone, that too “very severe cyclonic storm(VSCS)” as 

categorized in IMD cyclone category scale. Now, a person privy to chaos theory would say it’s 

possible. Not certainly probable, but not impossible either.  

Before we get started, I’ll talk a little more about cyclone Titli. VSCS Titli was a tropical cyclone 

that was deadly and destructive, it caused a huge loss and damage to Eastern India. Titli was the 

fifth named storm to form in the North Indian ocean in 2018. It originated as a low pressure system

on October 7 in Andaman sea, with IMD estimated peak winds of 150 Km/h on late October 10 just

hours before landfall. Titli made landfall over the eastern Indian state of Andhra Pradesh, and weakened

as it moved northeastward towards Odisha. By October 12, it got degenerate enough to die out. 

 

We’ll restrict ourselves only to cyclones in Bay of Bengal for smooth delivery of key points. In the context

of cyclones in the tropical ocean, we raise a few questions. One, how does a cyclone form, what sustains it

over time? Two, what limits the cyclones lifespan, why doesn’t it just stay there forever? Three, what 

decides it’s motion? You must have heard this or that cyclone is going to make landfall. Appropriately, why

does it go westward to the Indian coast after its genesis in the Bay of Bengal or Andaman sea?

 

To answer the first question, there’s a theory on the criteria of cyclogenesis which is as follows:

• Sea surface temperature higher than 27° C. The stratified Bay of Bengal is suitable as the surface 

  layers of Bay of Bengal gets warmer easily.

• Presence of the Coriolis force, implies the  initial disturbance should be away from equator

• Small variations in the vertical wind speed i.e, low vertical shear

• A pre-existing weak low- pressure area or low-level-cyclonic circulation.

• Upper divergence above the sea level system allowing lower level convergence to occur.

   

   

A cyclone as seen from space station

 

Well see, it’s like an entrance test of UPSC(or any other exam in India), there are lots of criteria, merely 

having 90% in intermediate class won’t make you eligible for the Job. Even with this hard and fast rule, 

some people do qualify; similarly, some disturbances do become cyclones. Hence, the beautiful thing  

about chaos is that there is also emergence. What are the odds of one of these criteria not being fulfilled?

It has a finite non zero probability. If one of these criteria doesn’t get satisfied, then the disturbance would

stop growing and no cyclone is formed. The second question is about the lifespan of cyclones. To put it 

bluntly, everything that is born has to grow and die eventually, including cyclones. Don't ask me about 

the red giant cyclone of Jupiter(no, seriously!! google about it). The key to sustenance of a cyclone once

it is formed, is again the above mentioned criteria. Provided that a cyclone is not making landfall, moisture

will be supplied to it, which in turn will condense to make rainfall and provide latent heat necessary for 

continued growth of the low pressure system. So, we can expect a cyclone to grow to its fullest extent 

till it remains away from land, assuming other criteria are not violated. Third question is about the processes

that determine motion of cyclones. For cyclones in Bay of Bengal which is in the tropics, we’ve easterly 

trade winds that push cyclones westward. Now there’s a catch, any moving parcel in the Northern 

hemisphere would move to the right of its motion direction. This is due to the presence of Coriolis

force which is a pseudo force that comes into play because of rotation of earth around its axis. The 

implication is the northward, northeastward or even eastward trajectory of the cyclone over time. But 

before it can divert to the extent of going eastward i.e, against the easterly trade winds, the cyclone owing

to its large length scale would usually make landfall and die out in the process. 

Coming back to Chaos theory; It is a theory based on non-linearity and limits to prediction. In other words

 a nonlinear system with incomplete knowledge of the initial conditions leads to limitation in prediction. 

Newton’s laws allow us to track the motion of a finite solid body over a time. On the contrary a fluid 

can’t be tracked perfectly as there is no such thing as a fluid parcel in reality. A fluid parcel undergoes

changes, it diffuses or gains some characteristics from the environment as it moves. In essence, we 

can know the condition(let’s say temperature) for an aggregate of fluid but not the characteristics of 

every entity of a fluid. And this lack of information piles up with time, eventually becoming strong 

enough to be noticeable. The principles of chaos theory are i) the butterfly effect, ii) limits of 

predictability, iii) order and disorder, iv) homogenization, v) feedback vi) fractals. We’ll discuss 

them in more detail.

The butterfly effect is at the core of the chaos theory. It says that a cyclone can be caused in the Bay

of Bengal due to a butterfly flapping their wings elsewhere. What it essentially means is that small 

change in initial condition can have huge change in results. It doesn’t mean that all cyclones are 

caused by butterflies only, it’s not true. Our lives are a product of interaction with peoples, so 

many classes and lectures, movies and songs, poems and debates, and yet maybe all started 

when you were with your best friend who likes similar things. Take your friend out of the equation,

it is entirely something else. The change may happen over a very long time, but the connection is 

real. The information about the initial conditions of a complex system are never perfect or whole

encompassing. Hence, with this incomplete knowledge we cannot hope to forecast the fate of a 

complex system. 

The order or equilibrium in a system is the absence of any disorder. But chaos doesn’t mean disorder,

 it’s more of a transition between the equilibrium(or order) of a system to the inequilibrium(or disorder).

This transition is handled by homogenization. Disturbance is inherent to a system, it can bring two 

water molecules closer together or take them to different parts of the vast ocean. In 2016, three 

drifters were released almost at the same time in the Arabian sea by researchers from CSIR-NIO.

The drifters stayed together for roughly 8 days before veering apart as time progressed. Within six

months time, each of the drifters were at very different locations, one was at the coast of Oman,  

second one was found at coast of Gujarat, while the third one was at central Arabian sea. This 

simple yet elegant experiment shows the chaotic behavior. 

Systems are prone to be chaotic with the presence of feedback. Consider the albedo effect of clouds

on environmental temperature. Incoming solar radiation heats up earth, leading to cloud formation 

which then act as a reflecting surface to the incoming solar radiation, hence reducing the environmental

temperature. But at the same time clouds are known to trap the outgoing infrared waves thereby 

increasing the temperature. The thickness, life and length span of clouds are not deterministically

known, which itself are dependent on various other factors.  

 

 

Fractals are the solutions or rather an approach to understand how systems in chaos works. The term fractal 

refers to a space of fractional dimensions. Let’s not delve into mathematics. Fractals are visual representations 

of solutions to chaotic systems which are obviously infinite in number.  A famous fractal is the Lorentz 

attractor (which happens to look like a butterfly to some imaginative people). Lorentz attractor shows 

that if we start from one initial condition, we can either be in state A or B after a given time. On the 

bright side, even though the development of the system from any specific state can’t be predicted, 

if we have sufficient solutions, it always results in the same kind of pattern, a butterfly. 

 

 

Nature is filled with exhibits of fractal properties, including but not limited to clouds, trees, the veins

in our body. Cognizance of the chaotic and fractal nature is important; e.g, from an atmospheric 

scientist's point of view, understanding the clouds itself would solve many of the problems. Our 

ecosystem, environment, economic and social systems are interconnected and appreciation is 

necessary to avoid any such action that is disastrous in the long term.