Category Archives: climate

Monsoon Clouds

The time when water vapor is no longer a constraint on cloud formation, the Monsoon provides for some spectacular visuals. The clouds are mainly formed due to convection over the Indian Ocean, which is why all the normal signatures of cloud formation like thunder and lightning are not very common. It simply pours. The time when thunder and lightning are common is when clouds form locally, during the months of April and May.

Space Craft?

This monstrosity is probably many kilometers long. An interesting thing to notice is the base of clouds, which is always nearly flat. The base is probably around 2.5 to 3 kilometers above the earths surface. This marks the top of the atmospheric boundary layer. Clouds this big are always bad news and seem to be cumulus congestus in the picture. This will eventually grow and bear rain. The formless sheets in front seem to be altostratus and normally dont bear rain. It is probably only in this season that you can see cumuli and stratus clouds together.

Same as above, more dispersed cumuli

Some really high clouds were also visible, indicating strong convection somewhere else. Cirrus clouds are normally found at a height of 5-6 kilometers and look very peaceful.

Cirrus, fibre like

And another shot of cumulus clouds, the smaller variety.

Cumului marching

Compare these with the clouds normally seen a few months before. The sky is way busier than in the months preceding the monsoon. Blame it on the winds.

Mysore and the rhythms of its Geography

Just finished the first volume of Fernand Braudel’s Civilization and Capitalism. It is truly a magnificent piece of work and would encourage anyone interested not just in the tales of kings and queens and their betrayals and affairs to read once in their lifetime.

The first thing you realise when you are done reading the Structures of Everyday life is the different time scales at which human life goes on. The fastest time scales deal with fashion, politics, wars and heroes, and has traditionally been the kind of history we learn. Then comes the structures of society and economy, which change more slowly, and the kind of change that the Marxists like to worry about. As I mentioned previously, movement (of something) is what is of most interest, and it is due to this reason the these two types of history are dominant. The third type, which Braudel’s book brings about is the material life of the masses, what they ate, drank, wore, built houses with, ploughed fields or carved stones with, moved from one place to another with and how these change. These facets of life are shown to change at a very slow pace, and to a large extent these determine what is possible or not. This is due to the fact that however quickly the more ‘enlightened’ people may want the world to change, the change must happen at the level of the majority of the population, and they change very slowly and reluctantly. Only violence on a large scale can change things at the pace the saviors of the world would want it to change, as the world has witnessed often.

Consistent with my views on evolution/history, the question I would like to pose is the following: How did the geography of Mysore determine how its people lived and interacted with each other and with the world around them? What are the constraints they faced, and how did they go about eliminating them or working around them?

The geography of the Mysore region is somewhat acceptable to humans at best. Being on an elevated plateau, the temperature are somewhat tolerable. The Ghats form natural boundaries on the east and the west and the south. If any water happens to flow on the right side of the Ghats, one can hope for life to exist, and luckily, there happen to be a couple of rivers which are the lifeline of the region, mainly the Cauvery, Tunga, Bhadra and the Krishna. However, these are not perennial like the Ganga and this is a huge constraint to the development of human societies by restricting transport and agricultural options. The soil, on the whole is not the greatest unless we look at the river valleys. The land is mostly uneven and thus prevents the construction of large scale irrigation works like canals. Indeed, the Mysore region was known more for its local tank irrigation (which is why there are so many lakes in the region) than for its canal system like in say Tamil Nadu or (for a better contrast) North India. The 1881 census listed more than 20000 irrigation tanks in the Mysore Region. The fact that this region receives rain from both the forward and retreating monsoons probably encouraged water harvesting activities further.

One of the major issues with large scale irrigation works is that it cannot be done by one or two villages — it has to be planned, executed and maintained centrally. My knowledge of Mysore history is not all that great, but I would expect the growth of strong, large kingdoms (native to it, not like the Vijayanagara Empire) to be less preferred as opposed to local chieftains because the local geography did not necessitate such structures. This would imply that there were strong local governance structures, something one has to explore in more detail.

When irrigation is not there, certain types of crops are out, especially rice. In fact, if one looks at the geography of crop cultivation in this region, rice and sugarcane were almost always grown very close to river beds, with the rest of the higher regions being cropped with millets and pulses. Rice, then, would be an unlikely candidate for staple food, and the food habits of villagers even fifteen years into the past bears testament to this fact. Rice was mainly an export item, which was sent to the various ports along the coast.

Agriculture being highly dependent on rainfall, any shortage was always a disaster. This induced people to hoard grains from good years. The population itself would probably have followed the vagaries of the rainfall, with a drought causing a famine and corresponding reduction in population. However, data to support this in precolonial india is simply not present. Also, it would have encouraged cultivation of more hardy crops like millets, giving another reason why ragi and its cousins are very popular in this part of the country. Go to the coast, and people prefer their boiled rice over ragi rottis.

Iron was the only mineral of any consequence during olden times that was found in the Mysore region, and it produced some of the finest steel the world has ever seen. It was exported to Persia (probably in return for Persian horses) and swords made from this steel are supposed to be the reason of the superiority of the Persian army over the Europeans for quite some time.

Thus, it can be seen that the geography and climate play a very important role in shaping the various activities that any culture or civilization has to perform to sustain itself. It constrains the type of polity and economy that can develop. When the British arrived, they probably would have felt suffocated by the economic environment they found themselves in, and resolved to change it to suit their needs. Capitalism arrived on Indian shores like an unstoppable force, only to meet the immovable object of the daily life of its inhabitants. How they managed to get it to move to their rhythms is another story.

Tales Clouds Narrate

Been meaning to write this for some time, but did not have enough pretty pictures to put in, so kept delaying it. Now that I think the pictures are pretty enough, here we go.

Clouds have fascinated people of various inclinations – from poets to physicists to farmers to nature lovers. They symbolize freedom, fertility and make sunsets magnificent. Apart from the metaphorical tales that poets imagine clouds to carry, they do tell us a lot of things, some of which I hope to convey through pretty pictures.

Clouds are among the most important factors driving our climate and definitely the least understood. The fact that they are so important derives from that fact that the climate is determined to a large extent simply by the amount of solar radiation that is trapped on earth, and clouds play a huge role in determining that amount. The atmosphere is almost completely transparent to incoming sunlight. The only thing that can reflect sunlight back to space are clouds, cooling the earth. Interestingly, clouds also absorb almost all the infrared that the earth’s surface emits, thus heating it. Depending on what type of cloud it is, clouds can either cause a net heating or cooling of the earth.

As a fluid dynamical problem, clouds are in a league all of their own. They display a nice interplay between dynamics and thermodynamics and are insanely difficult to model. If you look at the IPCC reports, the uncertainty due to clouds dominates any other factor. Of course, you can just numerically integrate equations of motion to see cloud development, but qualitative understanding is a recent thing.

Another useful thing about clouds is that they are the only opaque object in the atmosphere, and can be used to understand the state of the atmosphere. Since air is a fluid like water, it supports waves which carry momentum from one place to another and the best place to look for wave signatures is in clouds. The main waves in the atmosphere are Rossby and Internal Gravity waves. Rossby waves are huge, with wavelengths in thousands of kilometers, whereas Gravity waves are small enough to be seen. They are seen as regular patterns of cloud-no cloud and easy to spot, especially during the evenings.

Textbook picture!
Textbook Gravity Wave signature

The above is about as good a picture as you will find. Gravity waves normally will occur when denser air from the bottom will rise up and eventually come down due to their weight as compared to their surroundings. When I say small wavelength, it still is in the order of hundreds of meters! A couple more, but not as distinct.

Scattered, but still visible!
Still fainter, but nice looking cloud :)

Stratus clouds are thin (relatively!) and very large in spatial extent. They are a sign that vapor is unable to rise high due to strong density differences in the atmosphere, i.e, the atmosphere is strongly stratified. Thus, instead of rising high, it simply spreads out to a thin, large layer. This shows that the atmosphere is stable to rising motion – which is a bad thing! A stable atmosphere discourages convection of water vapor, which means less rain.

A more familiar sight in tropical areas like ours are cumulus clouds, which are normally associated with convective activity and rainfall. On nice and windy days, they can ‘march’ in step, as shown below.

Cloud March near home!

These can also develop into the thunderstorm version, which are called cumulonimbus.

Eye Candy!

Ok, that’s not a cumulo-nimbus tower, but you get the idea. Also, the sunset picture was too good to not put into the post :D Cumuli indicate either strong convection/ a weakly stratified atmosphere (which are actually cause and effect).

The height at which clouds start forming is another indication of the stability of the atmosphere. Cloud formation implies water vapor must condense, and this implies that the temperature must be low enough. If the clouds are low, it means that there are low temperatures at a low altitude, thus the atmosphere is quite stable. Higher up means the atmosphere has been well heated by the surface, like a kettle on a stove.

All in all, literally having your head in the clouds is good time pass!

Bridging Nature and Humanity

I personally find it quite strange to think of humans as apart from nature and vice versa, but after many interactions with people who think otherwise, it seems that I’m in a minority. If evolution is to be believed, we as a species (Dawkins would say individuals!) have evolved mechanisms to improve our survival rate, to the extent that we are now the most dominant species in terms of geographical reach and resource use.

However, our genes seem to have forgotten to encode limiting behavior, atleast with respect to resource utilization, which would enable us to live sustainably. Therefore, we have to resort to non-biological notions like stewardship and animal rights to keep ourselves in check. From where such notions arise, one really does not know. Nevertheless, questions in ethics, epistemology and ontology have interested us as much as questions in physics, math or chemistry.

Ancient scholarship, both Western and Eastern, never viewed either category as seperate from the other and, to quote a friend, did both physics and metaphysics. It is only recently that our world view has taken a schizophrenic turn, looking at billiard balls using differential equations (bottom-up) and guiding human behavior using teleology (top-down). It has been notoriously hard to reconcile these world views and thus each developed practically independent of the other.

No doubt, there have been attempts by one to encroach upon the other’s turf. Dawkins and like minded compatriots went one way, while the Christian Right in USA and Astrology try going the other. All in all, it seems unlikely that one or the other will have total dominance anytime in the near future.

Thus we are stuck with quarks on the one hand and The Goal Of Human Life on the other. For example, mainstream economics ignores nature by invoking the Axiom of Infinite Substitutability (One kind of good can always be substituted for another, thanks to human ingenuity), so if rainforests go, then we can always conjure up something to take its place. Marxist thinking takes the view that all human development is the result of economic processes, so trees and animals don’t even merit a mention – they are simply unimportant as far as human society’s development goes. On the other hand, we have climate models which put in a large amount of CO2 into the model atmosphere and see how things change, as though humans are just passive CO2 emitters who cannot recognize calamities and adapt their behavior (This seems ominously probable nowadays!). Each approach has value, no doubt, but it is obvious that neither economics nor climate modelling can actually solve the problems we face today.

One solution is for people with different outlooks to sit down and reach a consensus. My last experience with such an experiment was not very encouraging, and the recent spat between Rajendra Pachauri and Jairam Ramesh did nothing to to encourage anyone about interactions between politicians and scientists, I’m sure. The other solution, of which one is more optimistic, is for researchers to break  the new barriers and go back to a world view where one can engage with physics and metaphysics without being called a witch-doctor. Natural and social sciences are ripe for such a synthesis — we have finally reached a state where our metaphysics (explicit or otherwise) is affecting the earth’s chemistry and biology, maybe even the physics: while I don’t think we can change the Gravitational Constant anytime soon, but a few thermonuclear warheads here and there could change g=9.8 m/s2 to something substantially smaller!

Little known but impotant steps towards such a synthesis are being seen — ecological economics is bound to be mainstream before we kill ourselves, social ecology is bound to be important in the future too. Scientists seem to be getting more comfortable doing politics outside their institutions and politicians are learning some thermodynamics, thank heavens. The principle of  learning two subjects well, one closer to quarks and the other closer to the God side of the spectrum of human thought will serve researchers well in the future. Oh, and present day economics does not count on either side of the spectrum.

Climate and Engines – similarities and lack thereof.

After a whole semester of getting hammered by all kinds of climate related courses, one develops a great respect for the Earth and for the sheer dumb luck that we call life.

For example, a little closer to the Sun, we might have gone the Venus way, a little farther we would have been like Mars. Even then, we had to have the right amount of CO2 in the atmosphere, a surface dominated by water and its wierd behavior to survive. Also interesting is the fact that we have as a major component of our atmosphere a very reactive gas called oxygen whose fraction has not varied for a couple of million years. A little more oxygen, everything would have burned to cinders long time ago. A little less, the diversity of life that we see might not have existed. How silly bacteria and plants have managed to maintain the fraction of oxygen for this long a time period is quite a mystery!!

The Earth’s climate is like the holy grail for students of nonlinear physics, and thousands make a living by showing that we still have much to learn about it. That humans will never be able to accurately predict it over very long times scales is a given, so everyone has a gala time building models of increasing complexity to see how good we can become at this game of prediction in the future. All that being said, the basic physics behind climate are well understood, just that to predict it will require crazily large amounts of measurements of a crazily large number of variables, which just may not happen anytime before we cook ourselves.

To a first approximation, the earth is very much like an engine: it takes energy from the sun, does some work with it, and rejects the waste heat back to space. Since it has been doing this for millions of years, it seems reasonable to assume that what comes in must go out, otherwise this energy would build up within the earth, eventually destroying it. This kind of state is called radiative equilibrium.

So, what kind of work does the earth do using this energy ? Well, it causes winds, oceans currents to develop, helps photosynthesis and eventually (though not necessarily) forms something interesting like Aishwarya Rai. Every source of energy available to humans today, from flowing water to coal to Red Bull, all are sunlight in different forms (except nuclear, of course).

So, the main purpose of the earth’s weather (If one can impute purpose to it)  seems to be to distribute this energy to all corners of the earth. There are places like Antartica which really cannot be bothered by all this energy and reflect it back, other places like Kolkata and Chennai which seem to take in more than needed, but on the whole, the spread is quite even. The atmosphere seems to act like a piston, moving this way and that, taking excess energy from here and transferring it there. The poor atmosphere just wants to remain calm and steady, but somehow it manages to gain enough energy to become unstable. In the tropics where we live, the main mechanism by which it tries to regain equilibrium seem to be via rainfall – little wonder why it rains so much in the tropics!

The oceans take in quite a bit of this energy, keep it to themselves for a long time (unless something makes them throw it back out) and act like the flywheel – even if there is no much energy coming in from the sun (at night, say), they provide some energy back to the atmosphere, which is why coastal regions don’t really have too much variations in temperature.

But unlike human built engines, climate and weather don’t really bother about (probably due to lack of awareness) Carnot’s theorem. The source and sink temperatures for most of earth’s thermodynamic cycles is miniscule – the temperature difference for a good monsoon to happen is probably lesser than 10 degrees centigrade, amounting to an efficiency of almost zero! Makes you wonder if the Earth managed so well with zero efficiency thermodynamic cycles, why are we hell bent upon engines with huge contrasts in source and sink temperatures! Maybe we are just too impatient, and want to travel from Bangalore to Boston in less than a day. In contrast, ocean currents probably take years to do such a trip.

Come to think of it, huge gradients of anything are not really visible on earth, and where they exist they are quite destructive (think waterfall!). But even large gradients like waterfalls finally work to reduce the same gradient (these are called negative feedbacks). There are processes which enhance gradients (called positive feedbacks), and which are believed to have caused (and removed) the many Ice Ages that the earth has experienced, but on the whole this policy of keeping gradients small seems to have worked quite well for the Earth – Ice Age or otherwise, the Earth’s mean temperature does not seemed to have varied by more than 10 degree centigrade over millions of years. Individual areas might have huge variations, but as a whole it has been quite steady.

In contrast, a factory can have a variation of over 100 degrees over a single day! Obviously, factories cannot last millions of years. Any extreme event ( like human civilization ;) cannot sustain itself for long. But we seem to have made an ideal out of extremes : F1 racing, supersonic flights, George Bush, Bill Gates, Narendra Modi and so on, which does not seem to conform with sustainable behavior. One wonders whether sustainability addresses such issues. There is little doubt that our industrial civilization of the past 200 years will be a blip in the history of the Earth, but it remains to be seen (by who/whatever inhabits this planet millions of years from now) whether the Earth changes forever due to this extreme blip.