India has been invited to participate in a newly established US-led Gaza Peace Board, thrusting New Delhi into a pivotal moment in international relations. Analysts caution that becoming a board member may present substantial reputational dilemmas and strategic pitfalls. Alternatively
Since the US captured Venezuelan leader Nicolas Maduro in early January, pictures and videos chronicling the events have been crowded out by those generated with artificial intelligence, blurring the lines between fiction and reality.The endless stream of content ranges from comedic memes to
The never-ending list of security issues in 2026 has another victim and this time it is Google's popular Chrome web browser. The latest Chrome security warning in January 2026 has been posted by the Indian Computer Emergency Response Team (CERT-In) with a medium severity ranking
The Sports Ministry has finally taken note of the numerous complaints lodged by overseas shuttlers during the India Open last week and has sought corrective measures from the Sports Authority of India for the same, according to a report in PTI
Congratulations are in order as filmmaker Atlee and his wife, producer-actress Priya Atlee, just shared heartwarming news that their family is growing once again. After welcoming their first child, a son named Meer, in January 2023, the couple took to Instagram to reveal they're expecting a second
What does ‘visibility’ mean in weather science?
What does ‘visibility’ mean in weather science? Premium
A: In weather science, ‘visibility' is a colloquial term for a quantity called the meteorological optical range. It's defined as the distance a beam of light can travel through the atmosphere before its intensity drops to 5% of its original value.
In an older time, a human observer would stand at a point and look for predetermined landmark objects at known distances, e.g. a water tower at 1 km and a temple at 5 km. If the observer can clearly distinguish the object against the skyline, the visibility is at least that distance. At night, they used lights of known intensity.
Modern weather stations use sensors to measure the visibility. In the direction version, a transmitter shoots a laser beam at a receiver located a specific distance away (often 20-75 m). The receiver measures exactly how much light made it across. In the indirect version, a transmitter projects a beam of light past a receiver, not directly at it. If the air is clear, the receiver sees nothing; If there's fog or dust, the particles scatter the light, deflecting some into the receiver. The amount of scattered light is converted into a visibility distance.
The India Meteorological Department also classifies visibility depending on smog (i.e. smoke + fog) intensity. This scheme ranges from 500-1,000 m for ‘shallow fog' to less than 50 m for ‘very dense fog'. On January 18, the visibility in Delhi had dropped to ‘poor', i.e. 50-200 m.
Published - January 18, 2026 10:53 am IST
weather science / air pollution / Question Corner
Source: TheHindu
Related Posts: Red Alert In Delhi As Dense Fog Reduces Visibility Weather curtails England's strong start in Sydney IMD Weather Forecast India Weather Update Delhi, Noida and Gurugram weather The science of climate change and why India must look beyond green energy solutions Cold Weather Doesn’t Mean Less Water Rajkot Weather Forecast For India Vs New Zealand 2nd ODI Fog and frozen lakes as cold weather sweeps northern India Four metros to get 200 automatic weather stations to improve urban forecasts
YEIDA is set to launch a residential plot scheme this month in sectors 15C, 18 and 24A near Noida airport, with average prices around ₹35,000 per sq metre To meet the growing demand for homes near the upcoming Noida International Airport
1 minutes ago
As investments grows over the years, inflation also rises. Should Rs 3.5 crore will ensure wealth in 30 years? CA says this... New Delhi: CA Nitin Kaushik says that if one assumes that Rs 3.5 crore will be enough to feel rich after 30 years then it reflects their flawed understanding of long-term
Just now
The Supreme Court of India on Monday questioned the Delhi government over the timing of enforcing a new law that regulates school fees in the national capital, noting that it was introduced after the academic session had already begun. A bench of Justice P S Narasimha and Justice Alok Aradhe said
Just now
‘Women empowerment', ‘equality', ‘equity' and ‘feminism' are buzzwords which are hyped and have become the best personal branding weapons, especially in the digital era. We have progressed a lot but not enough for women to be able to work without the suffocating misogynist
Just now
Toyota Urban Cruiser EV: The Japanese automaker Toyota is set to launch the Urban Cruiser EV in India on January 20, marking its first-ever electric vehicle for the Indian market. Toyota Urban Cruiser EV: The Japanese automaker Toyota is set to launch the Urban Cruiser EV in India on January 20
Just now
Quote of the Day by Priyanka Chopra: “Perfection is boring anyway…” - a reminder that embracing our flaws makes us truly unique and authentic. Priyanka Chopra Jonas is a globally recognised Indian actress, producer, and philanthropist
Just now
Bajaj Electricals, part of the Bajaj Group, saw its shares surge 11% in early trade on Tuesday, January 20, touching an intraday high of ₹468 apiece, after the company announced its entry into the wires segment. Today's rally also provided a breather to the stock
Just now
Remarks from PMML Deputy Secretary General Haris Dar have surfaced just a day after reports detailed Lashkar-e-Taiba's alleged "water force" training in Pakistan. Pakistan's continued use of terror groups to spread unrest in India and Jammu & Kashmir has been exposed once again—this time
Just now
The International Cricket Council have not held any talks with Scotland about replacing Bangladesh at next month's men's T20 World Cup - but Scottish players would be ready if the call came. Bangladesh have told the ICC they will not travel to India for the T20 World Cup next month amid political
1 minutes ago
Tech giant Cisco sees India as a strategically very important market and will continue to invest there, its senior executive Jeetu Patel has said. Speaking to PTI here during the World Economic Forum Annual Meeting, the company's President and Chief Product Officer said India accounts for the
1 minutes ago
Telangana Chief Minister A. Revanth Reddy and other members of the State government's delegation to the World Economic Forum Annual Meeting at Davos reached Zurich on Tuesday (January 20, 2026). The delegation was accorded a warm welcome by overseas Telangana residents at the Zurich airport
1 minutes ago
United States President Donald Trump has issued a stern warning to France. He plans to impose a massive 200 percent tariff on French wine and Champagne. This action follows France's decision to decline an invitation to join Trump's proposed Board of Peace
1 minutes ago
US President Donald Trump on Monday said that he received a note from French President Emmanuel Macron, sharing a screenshot from an apparent message from the European leader. “Note from President Emmanuel Macron, of France,” Trump said in a post on Truth Social with the screenshot
1 minutes ago
India's T20 captain Suryakumar Yadav needs to find form against New Zealand. This series is a final World Cup tune-up. India has a strong record under Suryakumar. New Zealand is a tough opponent. Player selections like Shreyas Iyer or Ishan Kishan are key. Hardik Pandya and Jasprit Bumrah return
1 minutes ago
More than 16 years after the 26/11 Mumbai terror attacks, a powerful reflection on courage, values and quiet heroism has resurfaced, thanks to renowned Kannada actor and director Prakash Belawadi. His observations, shared on a recent podcast, have struck a deep chord
1 minutes ago
The International Monetary Fund has revised upwards its estimate of India's GDP growth in the current financial year 2025-26 to 7.3% from its earlier prediction of 6.6%. This upward revision, the IMF said in its January 2026 World Economic Outlook update released on Monday (January 19, 2026)
1 minutes ago
Monitors with built-in speakers are becoming a popular choice for users who want a cleaner, clutter-free desk without adding external audio gear. Options from brands such as BenQ, Acer, LG and others combine sharp displays with integrated sound, making them suitable for offices
1 minutes ago
Tata Tiago EV Facelift: The electric hatchback was seen fully covered in camouflage, indicating that design changes are being tested ahead of its expected launch in 2026. Tata Tiago EV Facelift: Tata Motors is planning to launch the Tiago EV facelift
1 minutes ago
Viral video claims crowd chanted against Gautam Gambhir in Indore. Fact check reveals edited audio and misleading context. A viral video claiming that the Indore crowd chanted “Gautam Gambhir haaye haaye” during the post match ceremony of the third ODI between India and New Zealand has
1 minutes ago
A: In weather science, ‘visibility' is a colloquial term for a quantity called the meteorological optical range. It's defined as the distance a beam of light can travel through the atmosphere before its intensity drops to 5% of its original value.A: In weather science
1 minutes ago
Rail services between Quetta and other parts of Pakistan were briefly disrupted after unknown men blew up a section of railway track near Dera Murad Jamali in Balochistan, adding to ongoing security concerns over repeated rail attacks. Dera Murad Jamali [Pakistan]: The train link between Quetta and
1 minutes ago
Shah Rukh Khan's brief interaction with a fan on stage at the Joy Awards 2026 in Riyadh has sparked a wave of online discussion, with many coming out strongly in the actor's defence. A video from the event has gone viral on social media, showing the superstar calmly handling an awkward moment while
1 minutes ago
The Karnataka government on Monday suspended Director General of Police (Civil Rights Enforcement) K Ramachandra Rao, a day after videos allegedly showing him engaging in sexual acts with women in his office began circulating online, The Indian Express reported
1 minutes ago
A Swiggy delivery rider was critically injured after being run over by a black Scorpio SUV in Gurugram. The incident took place in Sector 93, Hayatpur. A Swiggy delivery rider was critically injured after being run over by a black Scorpio SUV in Gurugram on Monday night
1 minutes ago
CG TET Admit Card 2026: The Chhattisgarh Vyavsayik Pariksha Mandal has released the CG TET Admit Card 2026 on its official website. Candidates appearing for the Chhattisgarh Teacher Eligibility Test can download their hall tickets from the official CG VYAPAM website at vyapamcg.cgstate.gov.in
1 minutes ago
The Punjab Government has approved the modernisation of major bus terminals in Ludhiana, Jalandhar, Sangrur, Patiala and Bathinda through a Public Private Partnership model to improve passenger convenience, safety and efficiency. The Punjab Government under the leadership of Chief Minister Bhagwant
1 minutes ago
Authorities said the blaze, which broke out around 10:00 p.m. on January 17, was brought under control after nearly 34 hours. At least 26 people have been confirmed dead and up to 81 others are reported missing after a massive fire tore through Gul Plaza on Karachi's MA Jinnah Road in Pakistan
1 minutes ago
