Air is an integral part of our lives. It cannot be seen or touched. Also, the air has no smell, but it is everywhere. It seems like the air is completely weightless, but it really isn’t. I wonder if scientists have experimented with weighing air and if have they yielded any results.

## Does air have weight?

The answer is definite: air is a mixture of gases, so it cannot be weightless. Nitrogen and oxygen make up 98%, and the other 2% are other gases. Each component of air comprises atoms and molecules – tiny particles.

Is it possible to prove that air has weight? To do this, a simple experiment is sufficient. It is necessary to inflate two balloons to the same size and tie them with a string to the ends of an ordinary pencil placed horizontally. In this position, the construction will keep the balance, since the weight of the two balloons is the same.

The next step is to pierce one ball – the pencil will immediately change position because of being overweight, as air is released from one ball. This experience proves that air has weight.

An interesting fact:the weight of air changes with altitude – it is lighter in the mountains and heavier in the flat areas. This is because it becomes more rarefied as the altitude increases. This means that the pressure decreases and the amount of oxygen and other substances decreases. Therefore, it is harder to breathe in the mountains. Near bodies of water, the air is heavier because there are more water droplets in the air.

The surrounding air forms the earth’s atmosphere and is subject to gravitational pull. Therefore, it exerts a certain amount of pressure on the surface of the earth. The density of air is 1.2 kg/m3.

## Past studies of air

The existence of atmospheric pressure was first proved by the scientist Evangelista Torricelli, a follower of Galileo Galilei. In 1643, he conducted an experiment with mercury. He used a 1 m long tube, which he filled completely with mercury. One end of the tube had an open hole and the other end had a sealed hole.

Torricelli also used another vessel with liquid metal. He lowered a meter-long tube with an open hole into the vessel. Mercury flowed out, but this process stopped at 760 mm.

Some force was pressing on the surface of the mercury at the top of the vessel. So it was proved that air has weight, and the mercury tube became the prototype of the barometer. And 760 mm of the mercury column is now considered the normal atmospheric pressure at 0℃.

## How do we know the weight of the Earth’s atmosphere?

So, it has been revealed that for every square centimeter of the Earth’s surface, air presses with a force of about 1 kg. Visually, each such centimeter can be represented as an air column. The atmospheric shell of the planet is also called an air ocean. Thus, the atmosphere comprises a huge number of such columns.

It remains to know how many cm² are contained on the surface of the planet. This information is known – the surface of the Earth is 510 million km², or 51 x 10⁷ square kilometers. 1 km contains 10^{10} square centimeters.

It turns out that 51 x 10^{7} x 10^{10} = 51 x 10^{17} cm^{2 }is the number of air columns on the entire surface of the planet. The same number corresponds to the weight of all the air on the Earth in kilograms or 51 x 10^{14 }tons.

An interesting fact:if air presses on each person with enormous force, then why, in this case, is this pressure remains intangible? The fact is that we also have air in our bodies to counteract and equalize the pressure.

To prove that air has weight is easy with simple experiments. It comprises various gases, and those comprise atoms and molecules, just like any substance. Gravity pulls on the Earth’s atmosphere, so there is a concept of atmospheric pressure. In an area of 1 cm^{2}, air presses with a force of 1 kg. If you do a simple calculation, considering the entire surface of the globe, the weight of all the air on the planet is 51 x 10^{14} tons.