High above the Pacific in 2018, the top of a colossal thunderstorm plummeted to the hellishly cold temperature of -111°C (-167.8°F), believed to be the coldest known storm cloud temperature ever recorded.
The temperature was picked up by a satellite on December 29, 2018, as it drifted over a severe thunderstorm that was raging in the South Western Pacific, approximately 400 kilometers (248 miles) south of the island nation Nauru. Describing the finding in a new study published in the journal Geophysical Research Letters, scientists at the National Centre for Earth Observation in the UK explain how this record-low cloud temperature came about.
Temperatures in Earth’s atmosphere generally decrease the higher you go. In the lowest section of the Earth’s atmosphere, the troposphere, air temperature can reach as low as -90°C (-130°F) in the tropics. Typically, storms remain within the troposphere and can reach an altitude of 18 kilometers (11 miles) above sea level. As they gain altitude, they get taller and taller, before the top of the cloud spreads out and high winds flatten the top of the cloud out into an anvil-like shape. These are known as cumulonimbus clouds, the only cloud type that can produce hail, thunder, and lightning
However, powerful storms are able to punch through this layer and rise into the stratosphere, the next layer up in the atmosphere. Known as an overshooting top, this dome-like protrusion into the lower stratosphere can drop to even lower temperatures.
In the case of this record-smashing thunderstorm in 2018, the tops of the clouds reached an altitude of over 20.5 kilometers (12.8 miles) above sea level, plunging their tips to just over ?111°C (-167.8 °F). Fortunately, this was also documented by the infrared sensors onboard the NOAA-20 weather monitoring satellite.
“This storm achieved an unprecedented temperature that pushes the limits of what current satellite sensors are capable of measuring,” Dr Simon Proud, study author and research fellow at the Department of Physics and the National Centre for Earth Observation, said in a statement.
Worryingly, scientists have been seeing more of these super-cold superstorms in recent years. Climate change appears to be a likely suspect, but the researchers aren’t yet sure what’s driving this worrying trend.
“We found that these really cold temperatures seem to be becoming more common – with the same number of extremely cold temperatures in the last 3 years as in the 13 years before that,” Dr Proud. “This is important, as thunderstorms with colder clouds tend to be more extreme, and more hazardous to people on the ground due to hail, lightning and wind. We now need to understand if this increase is due to our changing climate or whether it is due to a ‘perfect storm’ of weather conditions producing outbreaks of extreme thunderstorms in the last few years.”