Image shows subcontinent's land surface temperature, not air temperature used in weather reports
As heatwaves continue to ravage across India and Pakistan, a satellite image has been shared in multiple social media posts alongside a claim that it shows a weather temperature map of the two countries in April 2022. The claim, however, is misleading; the image shows the land surface temperature of the subcontinent, which is not the same as the air temperature that is used in daily weather reports.
The satellite image, which shows the Indian subcontinent in burning red colour, was uploaded on Facebook here on April 30, 2022, where it has been shared more than 900 times.
The post's caption reads: "April 30, 2022, #India #Pakistan the weather is really hot! The highest air temperature will be at 143°F (62°C) today."
The post circulated online as millions of people sweltered in a dangerous early summer heatwave across India and Pakistan in April 2022, AFP reported here.
However, the claim is misleading.
The image shows the land surface temperature, which is not the same as the air temperature used in daily weather reports.
The tweet reads: "The current extreme #heatwave in #Pakistan and #India as seen today, on the fourth intense hot day, by #Copernicus #Sentinel3 LST (Land Surface Temperature, not Air!). LST collected on April 29 shows max value exceeding 62°C/143°F. Gaps due to cloud/snow/nodata. #ClimateEmergency".
The current extreme #heatwave in #Pakistan and #India as seen today, on the fourth intense hot day, by #Copernicus#Sentinel3 LST (Land Surface Temperature, not Air!). LST collected on April 29 shows max value exceeding 62°C/143°F. Gaps due to cloud/snow/nodata. #ClimateEmergencypic.twitter.com/0MCMkcSg0t— ADAM Platform (@PlatformAdam) April 29, 2022
Land surface temperature is not the same as the air temperature, the metric used in daily weather reports, experts say.
"Land surface temperature refers to the radiated temperature from a given surface on the land, while the air temperature is the temperature of the air above the ground, often called by scientists two meters or near-surface air temperature," Cascade Tuholske, a geographer and postdoctoral research scientist at Columbia University in New York City, told AFP on May 4, 2022.
"While land surface temperature can be used as a proxy for heat impacts on human health and well-being, air temperature is a much more important metric for understanding how human health and well-being is impacted by heat."
Air temperature is the metric widely used to provide information for ordinary people, such as a weather forecast, said Omar Baddour, data application expert at the World Meteorological Organisation (WMO).
"The meteorological standard near-surface temperature refers to the temperature of the air taken at 2 metres above the surface," Baddour explained to AFP. "This is the temperature widely used by the meteorological services to provide information on temperature for ordinary people's use and other sectoral applications."
Clare Nullis, a media officer at WMO, said that "air temperature measured at two meters is the temperature we typically experience (if you think about the average height of an adult). So, this temperature and other elements like wind, humidity, etc., are part of 'weather.'"
Weather reports in India and Pakistan
As of May 12, 2022, neither countries have reported air temperatures higher than 60 degrees Celsius, contrary to the claims made in the misleading posts.
Temperatures in India have not crossed 48 degrees Celsius so far this summer, Mahesh Palawat, vice president of metereology and climate change at Skymet Weather, an India-based private weather-forecasting company, told AFP on May 10, 2022.
According to the Pakistan Meteorological Department (PMD), Jacobabad, a city in Sindh province, was the hottest place in the country in April 2022 when the mercury reached 49 degrees Celsius on April 30.