Topics Covered: Important Geophysical phenomena such as earthquakes, Tsunami, Volcanic activity, cyclone etc., geographical features and their location- changes in critical geographical features (including water-bodies and ice-caps) and in flora and fauna and the effects of such changes.
What to study?
For Prelims and Mains: Ozone layer and hole- factors responsible, effects and how to prevent it, reasons for variations in intensity, about Polar Vortex.
Context: Largest Ozone Hole Ever Recorded over North Pole Has Now ‘Healed Itself’ and Closed. This was announced by Scientists who were tracking the hole at Copernicus’ Atmospheric Monitoring Service (CAMS).
The ozone hole became the largest one ever recorded in the Arctic region spanning an area of over 620,000 square miles (or 997793.28 kms). It was formed due to unusual climatic conditions.
What caused a hole in the ozone layer?
The cause of the formation of the hole is attributed to the unusual weather at the poles.
The polar vortex has been recorded to be extremely powerful, and temperatures inside it have been very cold.
The unique cocktail of the powerful vortex and low temperatures generates Stratospheric clouds that react with CFCs and destroy the Ozone layer in the process.
Factors responsible for healing:
According to the scientists the closure of the hole is not due to the reduced pollution levels due to COVID-19 lock down.
The closing was because of a phenomenon called the polar vortex.
Ozone and its significance:
The ozone layer is one of the most vital atmospheric components of our planet.
It is responsible for protecting life on Earth from the harmful UV radiation from the Sun.
It is found mainly in the upper atmosphere, an area called the stratosphere, between 10 and 50 km from the earth’s surface.
The lack of the Ozone layer can have severe implications for people living directly under it. The most prominent effects are Skin Cancer and other possibly fatal skin diseases.
What exactly is a polar vortex?
It is described as a whirling cone of low pressure over the poles that is strongest in the winter months due to the increased temperature contrast between the polar regions and the mid-latitudes, such as the US and Europe.
- The polar vortex spins in the stratosphere.
- Usually, when the vortex is strongest, cold air is less-likely to plunge deep into North America or Europe. In other words, it forms a wall that protects the mid-latitudes from cold Arctic air.
- But occasionally, the polar vortex is disrupted and weakens, due to wave energy propagating upward from the lower atmosphere. When this happens, the stratosphere warms sharply in an event known as sudden stratospheric warming, in just a few days, miles above the Earth’s surface.
- The warming weakens the polar vortex, shifting its location somewhat south of the pole or, in some instances, ‘splitting’ the vortex up into ‘sister vortices’.
Effects of Polar Vortex:
The split higher up in the atmosphere can give rise to both, sudden and delayed effects, much of which involves declining temperatures and extreme winter weather in the eastern US along with northern and western Europe.
A sudden stratospheric warming also leads to a warm Arctic not only in the stratosphere but also in the troposphere as well.
A warmer Arctic, in turn, favours more severe winter weather in the Northern Hemisphere mid-latitudes including the eastern US.
Sources: Indian Express.