Q1.
Can you imagine what would happen if there were no atmosphere? Discuss your thoughts with your friends and teachers.
Answer
Life on the Earth would end. The way to answer this question is not to guess, but to take each job the chapter says the atmosphere does and remove it — the consequence follows from the job.
| What the atmosphere does (page 39) | What would happen without it |
|---|---|
| It is a mixture of gases vital for the survival of all living beings | No oxygen to breathe and no carbon dioxide for plants — animals, plants and human beings could not survive at all |
| It shields us from harmful radiation coming from the Sun, including ultraviolet | Ultraviolet and other harmful radiation would strike the surface directly; the ozone layer of the stratosphere would not be there to filter it |
| It regulates the Earth's temperature by trapping some of the Sun's energy and preventing it from escaping back into space | Heat would escape straight back to space at night. Days would be scorching and nights freezing — a huge swing every twenty-four hours |
| It is a key component of weather and climate, influencing temperature, humidity and air pressure | No wind, no clouds, no rain, no seasons — no weather of any kind, because there would be no air to move, hold vapour or carry pressure |
| Its mesosphere burns up meteorites | Meteorites would reach the ground unburnt, and the surface would be cratered like the Moon's |
Two more things would go, which are easy to miss: there would be no sound, because sound needs air to travel through; and the sky would be black even in the daytime, since it is air that scatters sunlight and makes the sky blue.
Why the Moon is the proof: the Moon has almost no atmosphere, and it shows every one of these effects at once — no weather, no sound, a black daytime sky, a surface covered in meteorite craters, and a temperature that swings wildly between the sunlit and shadowed sides. The atmosphere is not an extra that sits on top of the Earth; it is the reason the Earth is habitable and the Moon is not.
For your discussion: a good line of argument is to ask which of these would kill life first. Lack of oxygen would do it in minutes — but even if we solved that, the temperature swing and the radiation would make the surface uninhabitable anyway. That tells you the atmosphere protects us in several independent ways at once.