The stratosphere , also mentioned as stratosphere (with an accent on the syllable -fe ), is one of the layers of the atmosphere : the gaseous mantle that surrounds the planet Earth . This is the sector that extends between 12 and 50 kilometers in height.
Together with the troposphere and the mesosphere , the stratosphere forms the homosphere , which is the set of the three layers closest to the surface . In the specific case of the stratosphere, it is located in the middle zone of the homosphere.
Due to the absorption of electromagnetic radiation by ozone molecules, the temperature in the stratosphere increases with altitude. On the other hand, it is an atmospheric layer with a low level of humidity .
In the stratosphere is the so-called ozone layer , a sector with a high concentration of ozone that absorbs most of the high-frequency ultraviolet radiation. For years, the use of certain chemical compounds has generated a weakening of the ozone layer, known as the ozone hole .
The ozone hole means that the stratosphere no longer absorbs ultraviolet radiation as before, which is why these radiations reach the surface in greater quantities, causing various problems for people, such as increases in the number of cases of skin cancer, cataracts. and other disorders.
It is important to mention that the ozone layer, in reality, is not a layer that can be detected in the stratosphere, but rather a strip with a higher concentration of ozone than the rest of the atmosphere.
Between the troposphere and the stratosphere there is a transition zone known as the tropopause , in which the temperature tends to increase due to ozone and its relationship with ultraviolet radiation coming from the sun.
Another phenomenon related to the stratosphere is the impact it suffers from the passage of airplanes, since they usually move at an average height of 11 kilometers, precisely between the tropopause and the beginning of the stratosphere. With the growth that air traffic has had in recent decades, emissions of certain substances that remain between the upper and lower stratosphere have increased, such as water vapor, carbon dioxide, soot, and sulfur and sulfur oxides. nitrogen.
Currently, airplanes only generate up to 3% of the total emissions associated with the greenhouse effect , which does not have a considerable impact on global warming. This is not to say that they do not cause any major problems; On the contrary, given that the gases they emit remain in the upper part of the troposphere, the water vapor causes an increase in the probabilities of the formation of cirrus clouds, capable of retaining a greater amount of heat on the planet, which does contribute to global warming .
Another cause of environmental problems is the emission of nitrogen oxides, also from airplanes , something that is directly linked to the elimination of ozone in the stratosphere. Although the greenhouse gases emitted by these machines do not live long, they reach the stratosphere because they are released very close to it.
In the stratosphere, the air has a density equivalent to 90% of that present on the Earth's surface. In its lower layers, its temperature has an average of -56 degrees Celsius, and the speed reached by its air currents is around 200 kilometers per hour. As a curiosity, some research has revealed the presence of small microorganisms from outer space that live in the stratosphere.