The Earth The Physical Aspects

Scene 1: Beach B walking down the beach. “This is the marina beach in Chennai – the second longest beach in the world. There you can see the Bay of Bengal. Look how far the sea stretches out – we can see the sky touching the sea there. What we can see is only a very small part of the sea. Imagine how much bigger the whole earth must be !

Scene 2: Beach Walking on the beach “ The earth has many hidden wonders and today we will try to explore some of them. I am Balaji Sampath and I will help you explore and understand our home – the earth”.

Scene 3: Cut shots of the Earth Visuals “Earth is our home. A truly wonderful place. On the surface we have huge oceans and large continents. Sometimes from deep within the earth comes a rumble we call an earthquake. Sometimes the earth explodes and throws up huge amounts of lava. Even the oceans and continents are moving and constantly changing. The earth is and has always been a dynamic and ever changing planet. How des the inside of the earth really look? When was the earth born ? What is its life history ? In this we will try to answer some of these questions.”

Scene 4: Earth seen from outside and zooming in slowly into the earth. Our planet Earth is one of the 9 planets that go around the sun. We are now looking at the solar system from outside. You can see how big the sun is and how tiny all the planets are. The big dots are the outer planets like jupiter and saturn. You can hardly see the small planets closer to the sun. Let’s move closer to the sun. Ah! Now You can see that small blue green planet – the one that is third from the sun – that is the earth. How small and fragile our earth looks from space !

Scene 5: Earth from space picture –slowly zooming in This is how the earth looks from outside. A big round ball with blue oceans and green and white land on its surface. Above the surface is a thin layer of air that we call the atmosphere – with clouds and storms moving here and there.

Scene 6: Earth Atmosphere Where does the atmosphere end and outer space begin ? There is no clear height which marks the top of the atmosphere. We are now 260 km above the ground. If you go by at the speed of our usual buses – you will travel this distance in about 6 hours. This is the height at which space shuttles usually fly. Almost all the air in the atmosphere is below you.

Scene 7 B facing the camera “ On the surface air exerts pressure on us. When you suck air out of a bottle, air outside pushes the bottle in. 260 km above the air pressure is 100 crore times less than what you feel on here on the surface.” But even there, where there is so little air, in a small space like this (1 cc) there are still 100 crore atoms of air ! Imagine how much air there must here on the earth. (Animations of air molecules running around)

Scene 8 Yes – there is no clearly defined point where the atmosphere ends. It just fades away slowly into the space. But for all practical purposes, we can think of 260 km as the point where the atmosphere ends.

Scene 9: Animation – atmosphere, uv from sun hitting and ionizing the air The layer of air that stretches from 80 km above the earth’s surface to 260 km is the upper atmosphere – sometimes called the thermosphere because it is very hot. It has very little air. But the air atoms and molecules that are here absorb the dangerous x-rays and some of the Ultra Violet light from the sun and protect us. Atoms that absorb the light lose an electron and become “ionized”. Because the thermosphere is full of these ions, it is often also called ionosphere.

Scene 10: Ozone and Troposphere We are now 80 km from the earth surface and are moving closer and closer to the earth surface. We pass the stratosphere and are now 20 km from the surface. This is where we have the famous ozone layer. Ozone is made up of 3 atoms of oxygen. There is very little ozone here – but it can effectively stop most of the ultra violet rays and protects us and all life from burns and cancer. Chemicals from factories, fridges etc - have destroyed a lot of the ozone and also created holes in the layer. Exposing life to dangerous uv light.

Scene 11: Troposphere - animations The last 15 km of the atmosphere has 90% of the air – this is the troposphere. Here is where the weather happens, clouds are formed, it rains, winds blow, there are cyclones. Why is there so much action here ? All because of the sun ! Because of the cycle of days and nights and the cycle of seasons, the sun heats up some parts of the earth more than the others. Particularly the equatorially regions are much hotter than the rest. So here the air expands and rises up and starts moving away from the equator - towards the north in northern hemisphere and towards the south in the southern hemisphere.

Scene 12: Animations - can be just line drawings… But as the air rises and moves away from the equator, the earth is also continuously rotating and so is the air. The equator has a higher speed than the other parts. So as the air (which is rotating with the equator) moves away from the equator it is rotating faster than the surface. So air moving towards the north curves to its right and the air moving south curves to its left. This causes the rotating systems of high and low air pressure – the weather systems that bring us the monsoons, rain, cyclones, etc.

Scene 13: The surface At last we are now on the surface of the earth!