Monsoons and Mumbai


Every year towards the end of May, the city of Mumbai begins to change. People start to prepare for the coming of the Monsoon, which is itself derived from the word “mausam” in Arabic which roughly translates as a season. Perhaps in no other place than Mumbai, the might of monsoon is felt by such a large and varied section of people. All the residents, in all the areas of Mumbai, irrespective of their class do prepare for the annual coming of the monsoon. In Mumbai, everywhere you would see temporary structures being erected, plastic sheets of many colours and the most prominent blue tarpaulins being used to cover myriad of houses. It seems that the city itself is getting ready to greet the incoming monsoon. The various preparations done by people of all classes reminds one of festive preparation that families do. Some buy waterproofing for their bodies, some for their homes and shops and some for their vehicles. Some, who are very rich, even buy waterproofing for their pets. Government bodies like the BMC clean up the gutters and nallahs, which were freshwater rivers once, hard to believe when you look at their present states. You can see piles of cleaned up garbage and debris stacked neatly alongside the gutters manholes and nallahs. They say it helps in preventing floods. So, every year, like a seasonal change, you will see people cleaning them, and stacking the filth accumulated in these water bodies, both above the ground and underground in neat stacks.

Business establishments erect skeletons of bamboos and timber around the areas which are not covered. This happens in the case of hotels which have open-air seating areas. Then on these skeletons, they apply sheaths of water-proofing materials. At the end of it, the area is ready for use even in the heaviest rains. Shops which would sell, clothes and other stuff in other seasons, have umbrellas in their display. Even the street and traffic signal vendors start selling them. The umbrellas come in a variety of sizes, colours and designs. Males mostly carry black ones, while the females carry ones with a variety of colours. The umbrella is the protection of the commons against the rain. In the crowded local trains and buses, it is not seen kindly if you wear a raincoat and enter and transfer your wetness to others in the process. Umbrellas, on the other hand, can be folded and kept inside your bag. These are the kind of umbrellas, which are compact are the ones which are most common. The price range generally indicates the number of seasons that an umbrella will last. Also, the cobblers, who double up as umbrella repairers can be seen fixing broken ribs, handles and mechanisms of old umbrellas. Then there are the large ones, which you need to carry in hand, for they are larger than any bags you would usually carry. I myself carry one of the largest sizes available. Because when it really pours, the compact ones, though easy to pack and carry, aren’t going to protect you from getting wet in the Mumbai monsoon.

Then there is the rain footwear. The idea is that in the rains leather (even faux leather) will get damaged. Hence one should wear something made of rubber or plastic which is not affected by the rains. All the branded footwear companies have a stock of rainwear, which people buy as a preparation for the rain. But this is not for the real elite, they will wear their suedes even in the rains. From the by-lanes of Kurla, there emerge cheap replicas of the designer rainwear which are sold at less than 10th of the prices of the originals. They are sold outside the stations, on the streets, and in the shops. Each year, the designs, patterns and colours change depending on what is in vogue in the market.

People also buy protection for their mobile phones and wallets. Just before the rains pavement sellers, who sell a plethora of mobile trinkets and accessories, also start with selling waterproofing for the mobiles. Same is the case with the bags that working people and school children carry. Those not well off use covers of plastic to cover the valuables inside their bags. Good quality plastics are always in demand for such things. But now with the ban, we don’t know what will happen. Others purchase rain covers for their bags. Even with all these precautions mobiles and stuff inside the bags do get wet. And they get damaged.

They say when you are already anticipating something, the shock value isn’t that much as you would expect. But in the case of Mumbai rains, it is not so. Amongst the places I have lived in, the longest has been in Mumbai. Even then, I consider myself alien to this city, an outsider. I have seen and explored parts of it, yet I do not consider myself as a Mumbaikar. There are two primary reasons for this. The first is that even though after staying for more than a decade, I don’t use public transport for my daily commute. Neither the train nor the bus I use regularly. The two major forms of transport in Mumbai. So far, I have not stayed very far away from my place of work. Hence I do not have to suffer [safar?] daily travel. The other reason is that I have not yet made myself at home with the rains. It is not that I do not enjoy the rains, I do, but only for the first few weeks. Then it becomes torture. A melancholy if you will. The sunless skies for weeks on end are depressing enough, and then you have to prepare for the wetness. No matter how hard you try, the rains will get you. There hasn’t been a season where I haven’t got completely drenched. I have given up.

In case, I am caught unawares, without umbrella or any other protection. I just let the rain do its thing. I don’t fight it. But the city itself is fully prepared for it. Unless it is a literal flood, the city continues its routine as if, nothing has happened. All the supply lines will be working as they are supposed to. Waterlogging will produce delays in traffic and trains, but that is about it. If half the amount of rain that lashes Mumbai every season pours into any other metro it will come to a standstill. But Mumbai has made sure that the services operate despite this amount of rain. It is because of anticipation and will of the people to work.

The area of Mumbai is about 600 \, km^{2}, and the average rainfall in Mumbai is about 2200 \,mm. This essentially means that we have rainfall equivalent to about 2.2 \, m water present on the entire surface of about 600 \, km^{2}. So the total volume of water that Mumbai receives each year is

V_{Rain} = 600 \times 10^{6} \, m^{2} \cdot 2.2 \, m = 1.3 \times 10^{9} \, m^{3}

As a first approximation we can consider the rain drops to be of uniform size, and the diameter of the drop is about 1 \,mm = 10^{-3} m. So the volume of the drop is about
V_{Drop} = \frac{4}{3} \,\pi \,(0.5 \times 10^{-3} m)^{3} = 5.2 \times 10^{-10} \,m^{3}

Hence in each year the number of raindrops on Mumbai would be

N = \frac{V_{Rain}}{V_{Drop}} = 2.5 \times 10^{18}

As a better approximation we can take into account the fact that not all raindrops have the same size. We can then make a distribution of the raindrops according to their size. We can have a distribution of the raindrops according to their size as follows:

Type of
of drops
Percentage Volume m^{3}
Drizzle 0.5 15 6.5 \times 10 ^{-11}
Normal 1 70 5.2 \times 10 ^{-10}
Thunder 3 15 8.1\times 10 ^{-9}

So the total volume of our rail gets distributed according to the above table. Now we calculate the number of drops for each type of shower:

V_{Drizzle} = \frac{15}{100} \times 1.3 \times 10^{9} \, m^{3} = 1.9 \times 10^{8} \, m^{3}

Hence the number of drops in drizzle are:

N_{Drizzle} = \frac{1.9 \times 10^{8} \, m^{3} }{6.5 \times 10 ^{-11}} = 2.9\times 10^{18}

Similarly for normal shower we get

V_{Normal} = \frac{70}{100} \times 1.3 \times 10^{9} \, m^{3} = 9.1 \times 10^{8} \, m^{3}

Hence the number of drops in normal shower are:

N_{Normal} = \frac{9.1 \times 10^{8} \, m^{3} }{5.2 \times 10 ^{-10}} = 1.75\times 10^{18}

Similarly for thunder shower we get

V_{Thunder} = \frac{15}{100} \times 1.3 \times 10^{9} \, m^{3} = 1.9 \times 10^{8} \, m^{3}

Hence the number of drops in normal shower are:

N_{Thunder} = \frac{9.1 \times 10^{8} \, m^{3} }{8.1 \times 10 ^{-9}} = 1.1\times 10^{17}

So if we add all these up we get the total number of drops:

N = N_{Thunder} + N_{Normal} + N_{Drizzle} = 1.1\times 10^{17}+ 1.75\times 10^{18}+ 2.9\times 10^{18} = 4.7\times 10^{18}

This is not very different from our first rough estimate.

Just for fun or how to invite readers to immerse in your book

These problems are for fun. I never meant them to be taken too seriously. Some you will find easy enough to answer. Others are enormously difficult, and grown men and women make their livings trying to answer them. But even these tough ones are for fun. I am not so interested in how many you can answer as I am in getting you to worry over them.

What I mainly want to show here is that physics is not something that has to be done in a physics building. Physics and physics problems are in the real, everyday world that we live, work, love, and die in. And I hope that this book will capture you enough that you begin to find your own flying circus of physics in your own world. If you start thinking about physics when you are cooking, flying, or just lazing next to a stream, then I will feel the book was worthwhile. Please let me know what physics you do find, along with any corrections or comments on the book. However, please take all this as being just for fun.

From Preface of Jearl Walkers The Flying Circus of Physics

Anonymity and community in the age of RTI

(Draft under work.)

The year 2005 was a significant event in the history of India, as it
saw the introduction of bill for Right to Information. Under this
act any person could request data from government departments
pertaining to issues of interest. This was seen as first step
towards transparency of government of India, and indeed it was. The
RTI act was a weapon in hands of activists, who could now get the
required information officially. What was important also was that
there was a timeline which had to be adhered to while replying to
the RTI query. The information gathered from the various RTI queries
which individuals across the country empowered the citizens about
their rights regarding many issues. Also equally importantly RTI was
a tool for exposing the corruption running rampant in various
government departments. A RTI query could expose the irregularities
and bypassing of rules and regulations, leading to
corruption. There are many famous cases for their expose of big
names and massive corruption which were brought to light. (Some

Some people became what are now known as RTI activists. The RTI
activists were whistleblowers of the RTI age. These activists
exposed many scams at local and national levels. Such expose make
the people involved very uncomfortable. And as it happens in many
cases the people involved are very powerful and would not stop at
anything to attain their goals. In many such cases the RTI activists
were “easy” targets. By using the four-fold approach of /saam/,
/daam/, /dand/ and finally /bhed/ those in trouble try to stop the RTI
activists. Unfortunately in many cases, it turns out the activists
were killed as a result of their whistleblowing acts. (Give

What the RTI activists in various parts lack is a safety net, by
this I mean they lack support from people with similar
interests. They also lack, in a sense, a feeling of community who
will stand by them in case of such bad incidents. What can be done
for them? What kind of mechanism can result in their protection?
There was a proposed whistleblower bill, which if enacted will
provide security to such people. But the bill was not passed. Is
there any other option? Is there a way in which people can still ask
for information under RTI, without revealing their identity, so that
they cannot be “targetted” as whistleblowers. Is there a way in
which despite being anonymous there is a sense of community among
the activists of the RTI? It seems there can be an alternative way in
which we the people can provide a sense of anonymity and at the same
time that of a community to the RTI activists. What follows is
such a proposal which will try to cover these fundamental issues.

The proposal is to setup a front, which for lack of a name I would
call a /collective/ for now, which will mask those requesting RTI
from various government departments. The activists can send their
queries to the government departments through this collective. This
collective will in a sense create a buffer between activists and the
respective government departments, and associated problematic
elements. Since the RTI queries will be sent through this
collective, there will be sense of anonymity for the RTI activists,
as their names wouldn’t come under spotlight as in the earlier
case. One can also have a way in which the activist need not reveal
their identity to collective, that is we should also allow for
anonymous requests for queries. Some may point out that this might
be abused, but we have to give in this possibility hoping that pros
will outnumber the cons. Thus at no point we would have any data
regarding the identity of the applicant, hence we will not be able
to reveal it, when asked. This as will be pointed out can be abused,
but Thus the collective will form a mask for all the RTI
requests. Of coure people who want their name displayed for their
work, will be proud public faces of the collective. It would be much
more difficult to subdue or silence or attack the collective as it
would not be single point contact, but rather a distributed system.

So what do the activists gain by submitting to the collective,
apart from the anonymity. The collective will have a policy that
all the data that it receives from these RTI queries, will be put
up in public domain. This will in turn create a public archive of
information which will be accessible to anyone. Such a archive will
address many issues, like redundancy in filing of RTI queries, or
making the future RTI queries much more pointed and making material
available for researchers.

Such is a very rough proposal for the formation of the
collective. Suggestions and refinements in the proposal and
possible way of execution of this collective are needed.