In an earlier column, I had mentioned the interconnections among the three spheres – hydrosphere, atmosphere, and lithosphere. In passing, I have also mentioned examples of these connections. Today, I’ll expand on this topic a little more.

Remember that the three spheres (plus the biosphere which is where all the three meet and where life exists) are not neatly marked off areas of the world. We divide up Earth’s environment in this way only to make it convenient for us to study. There are no such divisions in nature. Therefore, we cannot clearly draw a boundary anywhere and say, for example, “This is where the lithosphere ends and the hydrosphere begins.” This is the way things are in nature and it is wonderful because things get very complex. Our use of separating out the spheres is an attempt to study and understand this complexity.

Then, we “re-assemble” the “pieces” and see how utterly marvelous nature is. It is sublimely beautiful and awfully fierce at the same time. Again, these adjectives – see, this is why you should pay attention in your language classes! – are our view. This is called anthropomorphization (attributing human form and characteristics to non-human phenomena or things).

It is difficult for us to separate out some of the things and study them while being immersed in them. Often, we need to step away from things and look at them from a distance. Literally. Human made – “artificial” – satellites help us do exactly this.

On YouTube, there is a wonderful documentary film based on data gathered by satellites sent up mainly by NASA and the ESA  (European Space Agency). These satellites are our “eyes in the sky” with which we can see many different phenomena on Earth and understand them.

Among a lot of other fascinating things, this documentary shows two very interesting connections.

Cold and hot

The Antarctic is very cold, right? Yet, it is vital to the warm regions where different forms of life (including us) live, thousands of kilometres away. Temperatures here drop to below –73˚ C (that’s less than 73˚C below 0!). That’s pretty cold, as you can imagine. Due to the connections among latitude, solar energy, and the global wind patterns, a clockwise circle of very powerful winds pushes the ocean water below. Water as deep as 2.5 km below the surface is moved by these winds – that’s how powerful they are.  This movement is called the Antarctic Circum-Polar Current. The winds are so strong that the latitudes 60˚S and higher are called the “Screaming 60s.” Together, these winds and the current, isolate Antarctica such that it does not receive the warmth of the surrounding world, keeping it very cold throughout the year.

When the salty oceanic water freezes to ice almost the same size as Africa. When the temperature at the surface of the ocean reaches a critical point, the surface water freezes.  As this happens, the salt is forced into the water below forming brine (highly salty water). This water is heavy and sinks. This is a lot of brine – tens of trillions of tonnes of it!

The ocean floor is full of vast mountains and valleys. As this brine sinks, it falls over the mountain sides, forming a really huge water fall under the ocean water. Huge water fall: 1 trillion gallons (US) of brine (to convert it to litres, use this: 1 US gallon = 3.7854118 liters); approximately the volume of 500 Niagara Falls! Maximum height of the water fall: about 3.2 km!

This brine travels as a current towards the Equator along the sea floor. Because the brine is very concentrated, it is heavy and travels along the sea floor (remember the term thermo-haline from an earlier column?) towards the Equator. This forms a part of the cold ocean floor current that circulates worldwide. That is rather slow, don’t you think?

As it approaches the Equator, it mixes with the warmer, more dilute ocean waters, and slowly rises. As this water travels away from the Equator, it cools, thickens, and sinks. And this cycle keeps going.

It is estimated that once it leaves Antarctica, its journey could take a thousand years to complete. When it returns to Antarctica, freezes and goes through the whole process all over again.

This is the perpetual Ocean Conveyor Belt.

No Antarctica, no currents. No currents, no life. No life … well, no exams, no geography study, no geography column. J

Desert and jungle

In the oceans, there are millions of microscopic living organisms called plankton. There are two types: (a) those that have chlorophyll and manufacture their own food are called phyto-plankton (phyto from Greek phuton ‘plant’, plankton from Greek planktos ‘to wander, to roam’) and (b) those that do not have chlorophyll are called zoo-plankton (from the Greek zōion ‘animal’; pronounced zow-oh-plank-ton). Thanks to nutrients that come from deep inside Earth, under the lithosphere, and into the oceans, vast numbers of phytoplankton form, grow, reproduce, and die.

The dead plankton (both types) sink to the bottom of the ocean and lie there. Over millions of years, the layer of plankton dead-bodies rise to great thickness.

Now, the Sahara desert is known to have once been the bottom of a large and ancient ocean. The Sahara sand is full of these dead plankton – it is called diatomite – spread over more than 62,160 square kilometres in the Sahara desert. Diatomite contains Phosphorus which is a crucial nutrient for living things to produce energy.

Seasonal winds blow the dust from the Sahara desert thousands of kilometres across the Atlantic Ocean to the skies over the Amazon rainforest in South America. This dust has a lot of diatomite in it. There, these particles, meet the water droplets in the rain clouds over the Amazon and dissolve into those droplets. When it rains on the Amazon, the dissolved Phosphorus reaches the soil and is taken up by the millions of living things in the jungle.

So, look at the connections among latitude, solar energy, wind, water, time, Earth’s rotation, and the Amazon jungle. Without these connections, we would not have the Amazon jungle!

Things you can do:

  • Watch the documentary (the link will open in a new tab/window) on YouTube.  It’s almost 2 hours long. Watch it your parents, or your friends. But remember to concentrate on what you are watching, or you will miss exciting information!
  • Make notes on the important points made in the video that can help you with the points below. You could also use a printed atlas (available at most stationery shops).
  • What are the two kinds of orbits that satellites are in, relative to Earth? Write out the differences between these types of orbits.
  • On an outline map of the world (available at most stationery shops), using your creativity (if you work in a group, you can come up with some amazing ideas), show:
    • How latitude affects the temperature on Antarctica.
    • How this latitude causes another factor that makes Antarctica cold.
    • Mark the major ocean currents and the crucial link between Antarctica and the world’s ocean currents.
  • On the same map, show:
    • The location of the Sahara Desert, the Amazon rainforest, these latitudes (0˚, 23 ½ ˚N, 23 ½ ˚S, 10˚N, 10˚S, 20˚N, 20˚S, 66½ ˚N, and 66½˚S), Pacific Ocean, and Atlantic Ocean.
    • Now trace the connection between the sun, latitudes, winds, and the movement of nutrients from Sahara to the Amazon rainforest.

(A version of this article appeared in the Deccan Herald Student Edition on 16 October 2014.)


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