Why in news? The Mungeshpur weather station in Delhi recorded a maximum temperature of 52.9 degree Celsius, an all-time record for any location in India. However, later, in an update, the India Meteorological Department (IMD) clarified that the record-breaking temperature was an error in sensor or local factor. The IMD is currently examining the data and sensors to verify the accuracy of the recorded temperature.

What’s in today’s article?

• Temperature Anomaly in Delhi
• Why do temperatures vary from place to place within the same city?
• Temperature records across the world

Temperature Anomaly in Delhi

• Anomaly
  • The maximum temperature across Delhi NCR varied from 45.2 degrees Celsius to 49.1 degrees Celsius in different parts of the city.
    • The IMD runs 20 weather stations in Delhi, 15 of which are automatic weather stations, or AWS, including Mungeshpur.
    • AWS record and transmit weather parameters without human intervention.
  • Mungeshpur reported 52.9 degrees Celsius as an outlier compared to other stations.
  • The IMD stated that this discrepancy could be due to an error in the sensor or specific local factors.
• Factors leading to high temperature in Delhi
  • The rain deficit contributed to the heat build-up.
  • Clear skies and westerly winds from Rajasthan where temperatures have hit 50 degrees have contributed to the heat in Delhi-NCR.
  • Climatology-wise, this is also the time of intense heating across northwest India, including Delhi-NCR.
• Heatwave conditions to reduce in next 2-3 days
  • As per IMD, heatwave conditions will reduce during the next 2 - 3 days due to:
    • gradual fall in temperature in association with approaching western disturbance,
    • rainfall/thunderstorm and
    • south-westerly wind blowing from the Arabian Sea to northwest India.

Why do temperatures vary from place to place within the same city?

• Temperatures experienced by a particular region are largely governed by weather. However, several anthropogenic factors also play a role, especially in a large urban centre such as Delhi.
• These factors include the concentration of pavements, buildings, roads, and parking lots.
  • In general, hard and dry surfaces provide less shade and moisture, thereby leading to higher temperatures.
• The material used to build infrastructure also has an impact.
  • For instance, places where most of pavements and buildings are made of concrete, witness warmer temperatures.
  • That’s because concrete can hold nearly 2,000 times as much heat as an equivalent volume of air.
• The geometry and spacing of buildings are a factor as well.
  • If a location is densely populated by buildings, surfaces and structures there become large thermal masses as they fail to release heat readily.
  • Very narrow streets and tall buildings obstruct natural wind flows that generally bring temperatures down.
• The heavy use of air conditioners in shopping malls and residential areas result in localised higher temperatures — ACs release an enormous amount of heat outdoors.
• These factors can collectively lead to the creation of ‘urban heat islands’ at a location.
  • These islands experience higher temperatures relative to outlying areas.
  • The likelihood of a place becoming an urban heat island is higher when it does not have trees, vegetation, and water bodies.
  • Natural landscapes bring down temperatures because they provide shade, and the processes of transpiration from plants and evaporation from water bodies produce cooling.

How temperature records are tumbling across the world?

• Statistics from around the world
  • United Kingdom crossed 40 degree Celsius for the first time ever in July 2022.
  • A small town in China’s northwest recorded 52 degree Celsius last year, the highest ever for that country.
  • In 2021, Sicily in Italy recorded 48.8 degree Celsius, the highest for Europe ever.
    • The highest ever temperature recorded anywhere on Earth, 56.7 degree Celsius in a place called Death Valley in the desert of California, United States, was recorded more than 100 years ago, in 1913.
• Study report by Carbon Brief (UK-based publication focused on climate change)
• The study showed that nearly 40% of the Earth had recorded its highest-ever daily temperature between 2013 to 2023.
• This includes places in Antarctica as well.
• Global Warming
  • The year 2024 was predicted to be extremely warm. Last year had emerged as the warmest year on record, globally, and the effect was expected to continue this year as well.
• Warming in India
  • The warming over India is not as pronounced as the world taken as a whole.
  • Annual mean temperatures over India have risen by about 0.7 degree Celsius compared to 1900 levels.
  • This is significantly lower than the 1.59 degree Celsius rise for average land temperatures across the world.
    • If oceans too are included, global temperatures right now are at least 1.1 degree Celsius higher than pre-industrial averages.
  • However, heatwaves over India are noticeably more severe.
  • In 2023, heatwave conditions prevailed even in February, technically a winter month for which heatwave thresholds are not even defined because they are not expected.