Essential Facts (Prelims) – April 14 , 2019


El Nino’s Impact on Monsoon

Category: Geography

  • El Nino is a phenomenon in the equatorial Pacific, in which sea-surface temperatures rise over a threshold of +0.5 degree Celsius (and cools by the same margin during alter ego La Nina).
  • There are a few other acronyms which one comes across while tracking El Nino. For instance, the Southern Oscillation Index, or SOI, that gives an indication of the development and intensity of El Nino or La Nina.
  • The SOI is calculated on the basis of the atmospheric pressure differences between Tahiti (South Pacific Ocean) and Darwin (Australia), separated by 8,569 km.
  • Another acronym is the ENSO (El Nino Southern Oscillation) which refers to the oscillation between the El Nino and the La Nina. ENSO shifts irregularly back and forth between El Nino and La Niña every two to seven years.
  • Under ‘normal’ conditions, though, the west tropical Pacific is warmer than its eastern basin. The warmer area of the ocean is also a source for convection and is associated with cloudiness and rainfall.
  • During El Nino years, the warmth shifts to Central and East Tropical Pacific and along with it, cloudiness and rainfall.
  • From 1950 to 2012, there were 16 La Nina years, with the monsoon rains ending up above or around average nearly every time. El Nino brought in five droughts during this period but on 14 other occasions, monsoon performance ranged from being well below-average, average, or even above-average.
  • El Nino has been generally known to suppress monsoon rainfall in India while La Nina increases it. El Niño years tend to be drier than average, but one of the strongest El Nino of the century (1997-98) produced a monsoon season with above-average rainfall for India.

Factors other than El Nino that Impact Monsoon

Category: Geography

  • Scientists claim there may be other factors that combine with the prevailing Pacific conditions to decide the fate of the monsoon.
  • Progressive heating of the land during April-May-June is one.
  • The extent of the Himalayan/Eurasian snow cover is another. Less snow cover means a warmer subcontinent, which can help to intensify the monsoon circulation and bring more rain.
  • Last but not the least is the ‘dipole’ effect nearer home, wherein the Indian Ocean mimics El Nino-La Nina in which the western and eastern basins warm up relative to each other every few years with associated impact on the monsoon. Warming up of the west Indian Ocean boosts a prevailing monsoon, and vice-versa.

Ethanol Production

Category: Sc & tech

  • A robust yeast strain that can produce up to 15.5% more ethanol when glucose or lignocellulose biomass — rice and wheat straw — is fermented has been isolated by researchers.
  • In India, ethanol production is mostly by fermenting molasses to meet the annual target of 5% blending of petrol with ethanol.
  • But with India setting a target of blending petrol with 10% of biofuel by 2022, other sources such as rice and wheat straw have to be considered.
  • Fermenting lignocellulose efficiently to generate more ethanol than what is currently possible is therefore necessary. To that end, the strain that has been isolated becomes important.

Origination of Life

Category: Sc & tech

  • Challenging a common perception, a new study suggests primitive ponds may have provided a suitable environment for creating the earth’s first life forms, more so than oceans.
  • The findings showed that shallow water bodies could have held high concentrations of what many scientists believe to be a key ingredient for jump-starting life on the earth: nitrogen.
  • If the origin of life required fixed nitrogen, then it’s tough to have the origin of life happen in the ocean. It’s much easier to have that happen in a pond.
  • Nitrogenous oxides were likely deposited in water bodies, including oceans and ponds, as remnants of the breakdown of nitrogen in earth’s atmosphere.
  • Atmospheric nitrogen comprises two nitrogen molecules, linked via a strong triple bond, that can only be broken by an extremely energetic event — namely, lightning.
  • Scientists believe there could have been enough lightning crackling through the early atmosphere to produce an abundance of nitrogenous oxides to fuel the origin of life in the ocean.
  • But the new study found that ultraviolet light from the Sun and dissolved iron sloughed off from primitive oceanic rocks could have destroyed a significant portion of nitrogenous oxides in the ocean, sending the compounds back into the atmosphere as nitrogen.
  • In the ocean, UV light and dissolved iron would have made nitrogenous oxides far less available for synthesising living organisms. In shallow ponds, however, life would have had a better chance to grow, mainly because ponds have much less volume over which compounds can be diluted. As a result, nitrogenous oxides would have built up to much higher concentrations.