Daily Current Affairs – Nov 28, 2023
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Southern Annular Mode
GS- I >> Geography>> Climatology
Context: Indian National Centre for Ocean Information Services (INCOIS), under the Ministry of Earth Sciences (MoES), has discovered that the Southern Annular Mode (SAM), an important climate pattern, plays a pivotal role in shaping the sea conditions across the Indian Ocean.
About Southern Annular Mode (SAM):
- The Southern Annular Mode (SAM) refers to the north-south movement of southern westerly winds occurring over timescales of 10s to 100s of years, also known as the Antarctic Oscillation.
- These winds blow consistently in the mid- to high-latitudes of the southern hemisphere.
- SAM is defined as the difference in the zonal mean sea level pressure at 40°S (mid-latitudes) and 65°S (Antarctica).
- In the Positive Southern Annular Mode, there is lower air pressure over Antarctica and higher pressure over mid-latitudes, strengthening and contracting the belt of westerly winds toward Antarctica.
- In the Negative Southern Annular Mode, the belt of strong Southern Westerly Winds expands northwards, affecting weather patterns in Patagonia and causing glacier advance, along with decreased Circumpolar Deep-Water upwelling on the Antarctic Continental Shelf.
About Indian National Centre for Ocean Information Services (INCOIS):
- INCOIS, established in 1999, operates autonomously under the Ministry of Earth Sciences (MoES).
- Its primary mandate is to deliver optimal ocean information and advisory services to society, industry, government agencies, and the scientific community.
Source: www.thehindu.com
Avian Influenza Virus (H9N2)
GS- II >> Social Justice>> Health
Context: There is an outbreak of human cases of avian influenza virus (H9N2) and clusters of respiratory illness in children in northern China.
About Avian Influenza Virus (H9N2):
- Virus type: H9N2 is a subtype of the Influenza A virus, mainly affecting birds.
- Transmission to humans: Although primarily a bird flu, isolated instances of human infections have been documented.
- The virus can jump from birds to humans, prompting concerns about its potential to trigger human influenza pandemics.
- Geographical distribution: H9N2 has been identified in various countries, especially in Asia and the Middle East.
- Human health implications: Human infections with H9N2 typically result in mild respiratory symptoms. The worry stems from the potential for the virus to reassort with other influenza viruses, giving rise to new strains with heightened virulence or transmissibility.
- Vaccine: H9N2 viruses display significant antigenic diversity, posing challenges for vaccine development. Targeting multiple strains may be necessary for effective immunity.
- Global health concern: H9N2 contributes to broader concerns regarding avian influenza viruses with pandemic potential.
- WHO’s risk assessment: Indicates a low likelihood of human-to-human transmission and a low case fatality rate among reported human H9N2 cases.
About Classification of Influenza:
The WHO categorizes the influenza virus, responsible for illnesses, into four types: A, B, C, and D.
- Epidemic-Causing Viruses: According to the CDC, only influenza A and B viruses are capable of causing epidemics.
- Type C Virus: The C type typically induces mild respiratory illness.
- Type D Virus: This type mainly affects cattle and is not known to infect humans.
- Subtypes of Influenza A: Among the influenza A virus, only subtypes are identified, based on two surface proteins: hemagglutinin (H) and neuraminidase (N).
Source: www.thehindu.com
Lightning
GS- III >> Disaster Management >> Natural Disaster
Context: Lightning kills 24 in Gujarat
About Lightning:
- Lightning is an electrical discharge caused by imbalances between storm clouds and the ground, or within the clouds themselves.
How does lightning occur:
- The discharges are generated in giant moisture-bearing clouds.
- As water vapor moves upward in the cloud, the falling temperature causes it to change into small ice crystals.
- They continue to move up, gathering mass until they are so heavy that they start to fall to Earth.
- This leads to a collision between smaller ice crystals moving up and bigger crystals coming down.
- Collisions trigger the release of electrons and free electrons cause more collisions.
- The top layer of the cloud gets positively charged, while the middle layer is negatively charged leading to flow between the layers.
- In comparison to the middle layer of the cloud, Earth becomes positively charged. As a result, some current gets directed towards the Earth.
- It is this flow of current that results in damage to life and property on Earth.
National Disaster Management Authority Guidelines:
- Early warning and Communication, lightning incidents can be detected by the ground-based Lightning Detection Network in real time.
- Prevention, Mitigation, and Preparedness Measures, including Emergency Plans, installing lightning arrestors, etc.
Source: www.thehindu.com
AstroSat
GS- III >> Science & Technology>> Space
Context: AstroSat has successfully detected its 600th Gamma-ray Burst (GRB).
About GRB: GRB are short-lived bursts of gamma-ray light, the most energetic form of light.
About Astrosat:
- It is the first dedicated Indian astronomy mission aimed at studying celestial sources in X-ray, optical and UV spectral bands simultaneously.
- It aim to understand high energy processes in binary star systems containing neutron stars and black holes,etc.
- It enables the simultaneous multi-wavelength observations of various astronomical objects.
Source: economictimes.indiatimes.com