Air and Air Composition

There is air all around us: outdoors, in the classroom, and in an empty dish. We usually do not see or smell air because clean air is transparent and odourless. However, we can feel the movement of the air, hear the wind rumble in the leaves, and see how the storm wind blows the sea waves.

Surely you have made air "visible" yourself. If you put an empty bottle without a cap underwater, bubbles will come out. In reality, it is the simplest scientific experiment. Unlike a normal game, an experiment always answers a question. If we ask the question, "Is the bottle empty?" before putting the bottle underwater, the game has turned into a scientific experiment. This gives us the answer: the bottle is not empty. There is something in the bottle that can be considered air, but scientists always need accuracy. To be sure that there was air in the bottle, we should learn more about the properties of air.

Air is a gas. Specifically - it is a mixture of gases. Air consists mainly of molecules of two substances: nitrogen and oxygen.

There are small amounts of other gases in the air. One of these is carbon dioxide, which is added to the atmosphere by many living organisms exhaling, and when fuels are burned. Plants need carbon dioxide in the air to grow. Combustion such as the burning of fuels, forest fires, and volcanic eruptions, produce carbon dioxide. Therefore, the amount of carbon dioxide in the air fluctuates a little.

There is always water in the air. In most cases, evaporated water molecules are evenly spread out between other molecules. When combined together, they may form small water droplets or ice crystals. They also make up the clouds.

Earth is surrounded by a layer of air called the atmosphere. It is as if our globe was located inside a larger, air-filled sphere. This sphere of air rotates and orbits along with the Earth.

The atmosphere is a layer of air that surrounds Earth

It is estimated that 4 to 5 billion years ago, a boiling, bubbling, fiery molten rock formed the interior of the Earth. The heavier elements (iron and nickel) formed the Earth's solid core, and the lighter elements rose to the surface. There is less pressure and heat away from the core, so a crust formed, but closer to the core there is still a lot of hot liquid rock. There used to be a lot more volcanoes all over the globe, and where Earth's crust was thinner, liquid rock and gas erupted from these volcanoes onto the Earth's surface.

There was no atmosphere yet. Instead, a thin layer of cosmic dust left over from the formation of the planets circulated the Earth. The Earth's first atmosphere was likely made up of the gases from the volcanoes: nitrogen, carbon dioxide, hydrogen, and water vapour. The Sun is at the perfect distance from the Earth so that water will condense and form oceans, but won't freeze entirely. Then, radiation coming from the Sun caused water to split into oxygen and hydrogen. The hydrogen escaped back into space, but the oxygen began to fill the atmosphere. Tiny cyanobacteria also helped by using the Sun's energy to consume carbon dioxide and release oxygen (like plants). This is how an oxygen-rich atmosphere developed. There used to be mostly tiny organisms that didn't need oxygen, but as the oxygen slowly filled the air, those organisms were poisoned by it, and were replaced by life that needed oxygen.