Air - the most widespread gas on Earth. Without it life on our planet is impossible. It has a number of unique properties which each person can learn.
What is air?
Air is a surrounding cover of Earth. Blue ""shirt"" - so call air, if to look at our planet from space, then it is visible that it is enveloped by a blue cloud which rises by height more than 1000 meters. Air represents the mix of gases consisting, nitrogen, oxygen, argon and carbon dioxide. Oxygen of air is necessary for ensuring activity of all beings on our planet and also for combustion of fuel and obtaining energy. Constant oxygen concentration in air is maintained by Earth flora. Green plantings are the real factory on production of oxygen, they absorb harmful carbon dioxide, and emit oxygen necessary for all.
What properties does air have?
To define properties of air, it is not necessary to have home laboratory, it is necessary to look only around. It is possible to tell with confidence that air transparent as we accurately see all objects which it surrounds. Air has no color: if to compare air to the known shades, then we will not find similar there. And whether the smell has air? To give the answer to this question, it is necessary to make brief experience: to spray before itself toilet water and to compare a smell before dispersion and later, then to clean orange and again to compare smells. After such experiment it will become clear at once that air has no smell, and all aromas which are felt in air belong to other gases which do not have any relation to air. So, air along roads smells of automobile exhausts, and on a glade - flowers, of bleaching powder air in the pool, and in the dining room - food smells. Various gases mix up with air and give it the specific aromas.
Smell in air after a rain
It is pleasant to most of people to breathe air which is felt after a rain. It has special attractive aroma which leaves nobody indifferent. But also it did not begin to smell air too. We already found out that air has no smell. It appears, during a rain the roots of trees and plants napityvatsya by moisture and begin to emit in the atmosphere the odorous oils having known for all ""began to smell after a rain"". This aroma even received the name - a petrikor (from the Greek petra - a stone, ichor — the liquid flowing in a body of the Greek gods). Some historians adhere to a position that people inherited love for a petrikor from ancestors for whom the rain meant survival.
Air has no own smell, but thanks to the properties, can mix up with other gases and transfer their aromas to various distances.