How heavy is air?

How heavy is air?

Until the XVII century this question would probably have caused a smile: because the air - void symbol, and it is clear that it weighs nothing. The then natural scientists reasoned that if the air though a little weighed, we would feel it!

And then came the Galileo and proved experimentally that the air has a certain weight. Today we know that the weight of the atmosphere enveloping the Earth is 5,1h10 ^ 15 tons, and the atmospheric pressure of a column in the body of each person - about 10 tons! And just because our bodies miraculously balances the external pressure is internal, we do not feel this monstrous cargo.

Air Earth shell heterogeneous in density, the cold air is denser and heavier than hot. When air is heated, its volume increases and the specific weight - decreases. This creates a lifting force pulling up balloons and airships, which is filled with hot air or light gas (eg, helium).

This phenomenon is extremely important for the existence of life on the surface of the Earth. When the sun's rays heat the air, it rises upward, and its place is taken by colder air. So there is a wind that moves the clouds formed over the ocean toward the land habitable, in need of rain water.

In itself, the formation of clouds and is due to this important law of nature - that warm air is less dense. Large amounts of water evaporate from the surface of the seas and oceans and rise upwards. There, in the upper atmosphere, the vapor meets cold air ceases to rise and condense in dense fog, forming a cloud. The more steam is cooled, the more it thickens, and, finally, the power of attraction draws the resulting heavy water drops back to Earth. And it starts dozhd.6027016199_18a61e7bfe_z

But for some reason, rains and gradually all the atmospheric water is poured on the earth in one sitting, which would lead to the flooding and the great detriment? The thing is that there is a complex and surprising natural mechanism for temperature balance due to which some of the water vapor remains in the atmosphere and continues to air travel, while the other part is condensed, putting on weight and, in the end, falls in the form of rain.

And now the question:

what the Jewish sages thought about the weight of the air and the influence of this factor on the amount of rain water well before the revolutionary discoveries of Galileo Galilei?

Verse Scripture full rapture at a Wonderland Creation "established for the wind (air) by weight, and water were prepared [He] as [the required]" 1.

Malbim ^ 2 comments:

"Installed wind weight", - the air has weight, weight. With this pair rise to clouds, since the lower layers of air is heavier than light water vapor.

And as a consequence, "And the water cooked He as" - the Creator has measured how much water will be at the top of the clouds and the clouds, and how many will fall as rain, but that it does not cover the earth, (as happened during the Flood). "

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Sources and notes

1) Job 28:25.

2) Malbim -abbreviatura name of Rabbi Meir Leib ben Yechiel Michel (1809-1879) - one of the greatest commentators of the Tanakh.