Question

What protects us from harmful radiation from the sun ?

Answer 1

Hint:The ozone layer is a layer of high concentration of ozone gas in the stratosphere, which is at a height between 15 to 35 kilometres above Earth's surface. The ozone layer acts as an invisible shield and protects us from harmful ultraviolet (UV) radiation from the sun.

Complete answer:
The atmosphere above us protects us from all the radiation that comes to the earth. It acts as a shield to the lives that are surviving on the surface of the earth. Earth's atmosphere reduces the temperature at the surface by reflecting most of the heat coming from the sun.The ozone layer protects us from the UV radiation, one of its types is known as UV-B, and it directly damages DNA and causes sunburn.

In short-term exposure it enhances skin ageing and significantly promotes the development of skin cancer. Due to long-term exposure to high radiation, UV-B threatens human health and damages most of the animals, plants and microbes, so the ozone layer protects life on Earth. It is also needed to process Vitamin D under the skin of mammals.

This layer of ozone in the stratosphere absorbs UV-A, UV-B and UV-C radiation from the sun. When an ozone molecule absorbs UV-B, it comes apart into an oxygen molecule and a lone oxygen atom. Later on, these two components again reform to the ozone molecule. Ozone gas is continuously forming and getting destroyed all the time in the ozone layer.

When UV-C light reaches the stratosphere, it’s completely absorbed by the oxygen molecules in the layer and never reaches the Earth's surface. UV-C separates oxygen molecules into oxygen atoms. These single atoms then react with other oxygen molecules to produce ozone. Hence, these reactions increase the concentration of ozone in the stratosphere.

Ozone is not the only gas that is present in the stratosphere. There is also nitrogen and hydrogen in the stratosphere. They are also an element in reaction cycles of destruction and production of ozone. Hence, these reactions decrease and also increase the amount of ozone in the stratosphere. When this cycle is undisturbed, the balance between the natural processes of ozone production and destruction maintains a natural ozone concentration in the stratosphere.

Note: Earth’s atmosphere is the reason why earth has life in it too! Since it acted as a shield the surface of earth cooled down and formed water. Then, in the process of evolution life on earth existed. The increasing concentration of CFC and other halogen containing gas in the atmosphere breaks the ozone gas and leaves a hole in the ozone layer. For this reason global warming, melting of ice at Antarctica and increasing sea level and other severe health issues like cancer is increasing. This breaking of the ozone layer and increase in temperature of the surface of earth is known as the greenhouse effect. To fight this and other environmental issues leaders of 195 countries have signed the Paris Agreement in 2016.