Question

what is ozone hole? how has it been formed in some parts of the upper atmosphere?

Answer 1

I hope you have understood

Answer 2

Ozone gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in stratosphere. There should be a balance between production and degradation of ozone in stratosphere.

Of late, the balance has been disrupted due to enhancement of ozone degradation of chlorofluorocarbons(CFCs). CFCs are formed by anthropogenic activities like use of refrigerators, pesticides, artificial solvents, foam products.

UV rays react with CFCs releasing Cl atoms. These Cl atoms degrades ozone.

It is only under certain meteorological conditions that ozone hole is formed. The conditions are

Cold temperatures during polar winter

Ice cloud formation

Special meteorological conditions to form the polar vortex.

Followed by the polar sun rise in spring.


However recently scientists have discovered that hole size is decreasing due to MontrealProtocol, 1987 to control the emission of ozone depleting substances. However there is another reason for shrinking of hole, i.e; due to rise of temperatures due to global warming, which is not suitable for ozone hole formation.