Although ozone is considered a problematic pollutant, when it is in the right place (in the upper atmosphere) - its contribution is great and vital to sustaining life. Ozone plays an important role in filtering out the harmful ultraviolet radiation that comes from the sun
Author: Dr. Netzah Parbiash, a young Galileo
In the previous section we asked why the Dead Sea is hotter than at the top of a high mountain located at the same geographic latitude, and we saw that the cause of this is the greenhouse effect which contains infrared radiation emitted from the earth. We realized that the thicker the layer of the atmosphere, the stronger the greenhouse effect, therefore it is hotter in low places than in the mountains that are even around them. However, the thickness of the atmospheric layer also has great significance when looking in the opposite direction: that is, the thickness of the atmospheric layer (which results from the differences in the surface height between valleys and between mountains) also affects the radiation that comes from space and passes through the atmosphere to the surface of the earth. This time we will try to understand why it is less dangerous to sunbathe in the Dead Sea than in Hermon.
a serious pollutant
Space, despite its name, is not empty space. Many heavenly bodies are in it, and some of them produce a flux of radiation. We previously mentioned the cosmic radiation made up of particles, the solar wind made of electrons, protons and alpha particles that are emitted at enormous speed from the sun. Electromagnetic radiation also comes from the sun and space. Fortunately for us, the Earth's atmosphere filters a large part of the radiation and prevents its penetration, thus allowing life to exist.
The Earth's atmosphere changes greatly with altitude - changes in temperature as well as in its chemical composition. To answer the question why it is less dangerous to sunbathe in the Dead Sea than in Hermon, we will focus on one phenomenon that is sometimes confused with the greenhouse effect. Have you heard of the ozone?
Ozone is a molecule made of oxygen atoms. Unlike the common oxygen molecule, which consists of two atoms and is labeled O2, the ozone molecule consists of three oxygen atoms, and is therefore labeled O3. Ozone is a poisonous gas with a pungent smell that causes breathing difficulties and various irritations. In areas of heavy industrial plants that result in its emission, it is considered a severe air pollutant.
The discovery of ozone
The first time scientists encountered ozone was probably in 1785, when the Dutch chemist Martinus van Marum conducted an experiment designed to investigate the properties of electricity. He built an electric generator that is powered by friction (electrostatic electricity), and the electric voltage created in the experiment reached a very high value of about 750 million volts! Van Marum and his team experimentally described a strange sensation and a pungent smell felt a few meters away from the generator. He noted in his notes that this is the "smell of electricity", and speculated that it is the effect of electricity on air (or oxygen). 55 years later, the chemist Christian Schneben noticed the same pungent smell when he conducted experiments in the electrolysis of water. Shanbein named the gas with the pungent smell that was created ozone, which is derived from the Greek word "ozine", which means "to smell".
the ozone layer
Although ozone is considered a problematic pollutant, when it is in the right place - its contribution is great and vital to sustaining life. In the Earth's atmosphere, ozone is found in a region called the stratosphere, where it forms a layer ("the ozone layer"). Ozone in the stratosphere plays an important role in filtering out the harmful ultraviolet radiation that comes from the sun. When the amount of ozone in this layer decreases, the "ozone hole" is created. When there is less ozone - electromagnetic radiation in the ultraviolet range penetrates through the Earth's atmosphere and may harm life on it, which is exposed to the sun's radiation. This is why it is important to wear a hat, expose yourself to the sun only in the early morning or afternoon and use sunscreen.
It is important to note that in the case of the hole in the ozone, and also in the case of global warming that is probably occurring due to an increase in greenhouse gas emissions - the blame is probably man's industrial activity; This disrupts the natural conditions on Earth. However, although both phenomena are apparently caused by humanity, they are not related to each other.
To answer the question we opened with, let's put the hole in the ozone aside for a moment, and say that the thickness of the atmospheric layer affects the degree of filtering of different types of radiation, with an emphasis on the more harmful ones. Therefore, when we are on the shore of the increasingly drying Dead Sea, we are in the lowest place in the world, at a height of about 430 meters below sea level. This means that above us is a layer of atmosphere that is 430 meters thicker than that on the coast of the Mediterranean Sea (sea level) and about 2.5 kilometers (!) thicker than that on the summit of Mount Hermon. Therefore, even though Hermon is cold and chilly compared to the Dead Sea, it is usually warm there - the radiation coming from space is stronger in Hermon than in the Dead Sea. And if we visit the snowy Hermon in winter? Then the phenomenon will be many times more serious! why? Because the white snow reflects the radiation, and if we don't protect ourselves accordingly (radiation filter, hat, sunglasses, etc.), we will find ourselves freezing from the cold, but in the exposed areas of the body - getting sunburned!
*The author is the Scientific Vice President of Carso Science Park in Be'er Sheva
The article appeared in the July issue of Young Galileo – Monthly for curious children
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