All through human history, we have engaged with our environment, Earth, in many ways. Science is but one such way. So, is anything that is not science-based wrong? Should it be discarded as ‘mere superstition’? As a geographer, I find both of them fascinating.

Many years ago, I read somewhere: Take away all the scientific, technological, and cultural accomplishments of humankind and we end up owing our existence to two basic facts: the fact that there are a few millimeters of topsoil, and the fact that it rains. Interesting thought, though we probably shouldn’t take it too literally.

Of these two, I want to share a few thoughts with you about rain today.

All around the places I frequent, if I happen to pass an English-medium nursery school, I hear little children loudly reciting Rain, rain, go away! Geographically speaking, that is an abhorrent thought for us in India!

That rhyme, as many English rhymes do, comes to us from a distant landscape and culture that have little or no bearing for us in most parts of India. The weather in England has always been a dampener (literally!) because it rains so much and so often!

Even in these days of climate change, and abnormal weather patterns, sunny days are a huge deal in England.

When I was a child, for our English classes we had a textbook published in England, The Tales the Letters Tell. Nice books. In that, I used to read this phrase, “One fine sunny day…” I asked my uncle what that was all about. Here, if I went out to play in the sun, I used to get yelled at! “Come back inside to the shade! Why are you out in the sun?” That’s when he explained English weather and its problems.

Science

Meteorological science and advances in computer technologies have made it increasingly possible for us to predict weather more and more accurately. We are beginning to better understand the atmosphere and its processes better. Super computers are now able to do billions of calculations within seconds and give us the results.

With all these, we are still unable to predict the monsoons as precisely as we would like to.

The system that we call Earth is phenomenally complex and to get a full understanding of how it works is a formidable undertaking. But we are making progress.

The scientific approach holds that the Earth system can be understood using mathematics and physics … it is, indeed, a system governed by the laws of physics called thermodynamics, something you are likely to study in college, if you choose physics as one of your subjects.

Four spheres

Look at the diagram I have given here. The various spheres of the Earth system are inter-connected. Any changes in one, leads to changes in all the others. Those changes trigger further changes and so on.

All this happens because of inequality!

The Sun provides a major part of the energy that drives Earth’s system. It heats the atmosphere (gases), hydrosphere (mainly liquid), and lithosphere (solids: rocks, soils) at different rates.

 

The interacting spheres of the Earth system. (Click on the image to view a larger version in a new tab.)

What causes the difference in heating? Put very simply, the variations in latitude, altitude, and nearness to each other.

This difference in heating causes unequal spread of the heat energy. Solid (land) heats up and cool down more quickly than liquid (water). The sun heats the ground and bodies of water by its radiation. The ground or body of water heats the air above it by conduction (i.e., they are touching each other). The heated air rises, moves about, and spreads the heat by convection.

All this amounts to massive transfer of heat energy among all three spheres.

Water

Water is part of the hydrosphere.

Water in the hydrosphere and lithosphere heats up due to solar radiation, becomes water vapor (a gas), rises into the atmosphere, and joins the other gases. This involves two processes: evaporation (the water vapor produced by solar energy), and transpiration (the water vapor produced when living things breathe). All this is the movement of heat and water from the hydrosphere into the atmosphere.

When the water vapor in the atmosphere cools and condenses, it becomes too heavy to stay up there. Depending on the temperature conditions, it comes back to the lithosphere and the hydrosphere in the form of rain, snow, sleet (freezing rain), or hail stones. This is what we call precipitation.

The water we get in our precipitation could be coming to us from far away. This is because the atmosphere is always moving in different directions at different altitudes. Winds carry water vapor from place to place.

Based on centuries of research our understanding of how these things work is increasing.

However, that is not the whole story for a large number of people. There are other ways for them to look at rain.

I’ll share that next week.

Explore:

  1. How are Great Britain, United Kingdom, and England different?
  2. Are glaciers part of the lithosphere or hydrosphere?
  3. These spheres … do they actually exist or are they our way of trying to make sense of the system?
  4. In what ways are you contributing to the flow of water in the Earth system?
  5. If the energy from the sun were to affect all of Earth equally, what would happen to the Earth system?

Join us for the 6th International Geography Youth Summit, IGYS-2020,
24-26 July 2020, Bengaluru

A version of this article appeared in the Deccan Herald Student Edition on 27 October 2019

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