Thursday, 18 June 2015

How Global Warming has Brought Down the Intensity of Rainfall?


There has been a steady decrease in the amount of monsoon precipitation in the Indian subcontinent over a decade. The experts say it is due to the phenomenon of global warming. The air circulation takes place only when there is enough temperature gradient between the ocean waters and the landmass.  Due to the global warming, this temperature gradient in the region is steadily decreasing. This has lead to the retention of less water in clouds that form the monsoon system.  The authorities claim that the decrease in gradient has slowed the advancement of the monsoon system in the equatorial region. Unless and until the efforts are taken to reduce the global emission of the heat-retaining gases to the atmosphere, the region is progressively going into the age of the erratic monsoon season.
monsoon season

Impact of Global Warming

Due to the retention of greenhouse gases, the amount of heat radiating back to the outer space from the earth’s surface has significantly reduced. In normal case, the naturally present gases do not interfere in this process. Due to the steady increase in the emission of greenhouse gases due to the burning of fossil fuels and burning of the forests, the amount getting radiated to the outer space is getting lower. In other words, most of the reflected heat is retained in the atmosphere by these greenhouse gases. As a result, there is a significant reduction in the temperature gradient across the sea-land interface. The gradually dwindling temperature difference is also making small local air turbulence over the sea or ocean. These atmospheric turbulence hinder the free movement of the monsoon system over the seas. They also interfere with the amount of water vapour released from the sea. This is the reason the monsoon clouds are progressively getting drier with the passage of time
monsoon system

Dust Storm Formation

The region near India and Pakistan has seen a lot of deforestation over the period of two decades. As a result, the winds from the west that gets generated due to the prevailing air turbulence in the region pick up the dust en route. These dust storms are not good for the respiratory organs. These have tiny particles of dust that can go easily into the air passage and trigger allergic reactions in the lungs. That is the reason one can see an increase in the incidence of seasonal asthma in areas where the dust storms occur as a prelude to the arrival of monsoon season. These dust storms regularly hit many northern states and central states just before the arrival of rainy season. These dust storms also block the free movement of monsoon clouds and even drain the amount of moisture contained in them. These interactions between the dust clouds and the monsoon system make the prediction of rain in a region highly difficult.  The monsoon cloud system is a huge cloud mass that spans many square kilometres. These dust storms only block the movement for some time till the time it weakens out. Yet, they can spoil the free precipitation of cloud masses at the intended areas. This phenomenon can be reversed with the reforestation of the lands in the area through which the monsoon clouds move.

dust storm