The Ozone Layer

The stratosphere contains a form of oxygen called ozone. Ozone is a molecule composed of three oxygen atoms. The chemical symbol of ozone is O3. Oxygen molecules make up about 21% of all gases in the earth's atmosphere. They consist of two atoms of oxygen and are labeled O2. Most ozone found in our atmosphere is formed by an interaction between oxygen molecules and ultraviolet radiation from the sun. When ultraviolet radiation hits an oxygen molecule, it may cause the molecule to break apart into single atoms of oxygen. These single atoms are very reactive, and a single oxygen atom can combine with a molecule of oxygen to form ozone. The individual ozone molecules make up what we call "the ozone layer." It is not, however, a very thick layer. There are usually fewer than three ozone molecules for every ten million molecules of air. That is why ozone is known as a trace gas, meaning that only trace (very small) amounts are present. We are fortunate that these small amounts make a big difference.

The photochemical mechanisms that give rise to the ozone layer were worked out by the British physicist Sidney Chapman in 1930. Ozone in the earth's stratosphere is created by ultraviolet light striking oxygen molecules containing two oxygen atoms (O2), splitting them into individual oxygen atoms (atomic oxygen); the atomic oxygen then combines with unbroken O2 to create ozone, O3. The ozone molecule is also unstable (although, in the stratosphere, long-lived) and when ultraviolet light hits ozone it splits into a molecule of O2 and an atom of atomic oxygen, a continuing process called the ozone-oxygen cycle, thus creating an ozone layer in the stratosphere, the region from about 10 to 50 km (32,000 to 164,000 feet) above Earth's surface. About 90% of the ozone in our atmosphere is contained in the stratosphere. Ozone concentrations are greatest between about 15 and 40 km, where they range from about 2 to 8 parts per million. If all of the ozone were compressed to the pressure of the air at sea level, it would be only a few millimeters thick. Ten percent of the ozone in the atmosphere is contained in the troposphere, the lowest part of our atmosphere where all of our weather takes place. Tropospheric ozone has two sources: about 10 % is transported down from the stratosphere while the remainder is created in situ in smaller amounts through different mechanisms.

Ozone are molecule made up of three oxyzen atoms. O3 in the scietific term. There is a layer of ozone gas in our atmoshpere, it's filtering the UV light that reach our Earth. In fact it's a wonder for these gas at this mass number could float up there in the sky. (O2 should be lighter than O3)

no...not at all